P06A1 Variable A/C Compressor Control Circuit Low

What does it mean?

This is a generic powertrain diagnostic trouble code (DTC) that applies to many OBD-II vehicles (1996-newer). This may include, but is not limited to, vehicles from General Motors, Honda, Dodge, Ford, BMW, Mercedes, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

OBD-II trouble codes P06A0, P06A1, and P06A2 are associated with the variable A/C compressor control circuit.

The purpose of the variable A/C compressor control circuit is to engage and disengage the compressor at the appropriate time to maintain the desired temperature inside the vehicle’s cabin. The ECU receives voltage signals from various components to detect potential malfunctions within the system.

The variable A/C compressor control circuit includes several components to accomplish this process. Most newer automobiles are equipped with air conditioning, which is an essential element for this circuit to function correctly.

When the engine control unit (ECU) detects abnormally low electrical signals in the variable A/C compressor control circuit, code P06A1 is set, and the check engine light is activated.

A typical air conditioning compressor:


P06A1 Air Conditioning Compressor
How severe is this DTC?

The severity of this code is moderate to severe depending on the specific nature of the problem. While it is a convenient feature for the user, air conditioning malfunctions can progress, leading to extensive repair requirements when not corrected in a timely manner.
What are some of the symptoms of the code?

Symptoms of a P06A1 trouble code may include:

The air conditioner will not work properly
Check engine light illuminated

What are some common causes of the code?

Causes

of this P06A1 code may include:

Faulty A/C compressor
Faulty A/C solenoid (if applicable)
Undercharged or overcharged system
Clogged orifice tube or dryer
Faulty climate control
Faulty A/C relay
Blown fuse or fusible link (if applicable)
Corroded or damaged connector
Faulty or damaged wiring
Faulty ECU

What are the troubleshooting steps for P06A1?

The first step in the troubleshooting process for any malfunction is to search for Technical Service Bulletins (TSBs) for the specific vehicle by year, model, and powertrain. In some circumstances, this can save you a lot of time in the long run by pointing you in the right direction.

The second step is to locate all components of this circuit and perform a thorough visual inspection to check that the associated wiring does not have obvious defects such as scraping, rubbing, exposed wires, or burn marks. Then, check the connectors for security, corrosion, and damaged pins. This process should include the A/C compressor, associated sensors, relays, and the ECU.
Advanced Steps

Advanced steps become very vehicle-specific and require appropriate advanced equipment to function accurately. These procedures require a digital multimeter and vehicle-specific technical references. The ideal tool for this troubleshooting process is an A/C diagnostic machine, if available.

This specialized equipment is essential for locating the source of the malfunction by identifying leaks and verifying proper pressures in the system. High and low side gauges will also validate the integrity of the A/C compressor and associated components. Restrictions within the system, such as a clogged orifice tube or dryer, will also be identified. The proper amount of refrigerant in the system also plays a key role in the operation of this circuit. Safety switches, fuses, and fusible links are often incorporated to prevent damage to the A/C compressor.
Voltage Checks

Specific troubleshooting guidelines must be referenced to determine the required voltage ranges for various A/C components. Depending on the configuration, several components are integrated, including the A/C compressor, relays, and solenoids for certain applications. The climate control in newer automobiles can make the troubleshooting process extremely complicated in some cases. Voltage requirements vary depending on the specific year and model of the vehicle.

If this process identifies the absence of a power source or ground, continuity tests may be required to verify the integrity of the wiring, connectors, and other components. Continuity tests should always be performed with the power disconnected from the circuit, and normal readings for wiring and connections should be 0 ohms of resistance. Resistance or lack of continuity is an indication of faulty wiring that is open or shorted and must be repaired or replaced.
What are the common repairs for this code?

Replacing the A/C compressor
Replacing the A/C solenoid (if applicable)
Replacing the orifice tube or dryer
Replacing the blown fuse or fusible link (if applicable)
Repairing the A/C system leak
Cleaning corrosion from connectors
Repairing or replacing faulty wiring
Evacuating and recharging the system
Flashing or replacing the ECU

Misdiagnosis can lead to replacing the A/C compressor or other associated components when wiring, connectors, or incorrect charge are the cause of the problem.

I hope the information in this article has been helpful in pointing you in the right direction to correct the issue with your variable A/C compressor control circuit error code. This article is strictly informational, and the technical data and service bulletins specific to your vehicle should always take priority.

P06A2 Variable A/C Compressor Control Circuit High

What Does It Mean?

This is a generic powertrain diagnostic trouble code (DTC) that applies to many OBD-II vehicles (1996-newer). This may include, but is not limited to, vehicles from General Motors, Honda, Dodge, Ford, BMW, Mercedes, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

OBD-II fault codes P06A0, P06A1, and P06A2 are associated with the variable A/C compressor control circuit.

The purpose of the variable A/C compressor control circuit is to engage and disengage the compressor at the appropriate time to maintain the desired temperature inside the vehicle’s cabin. The ECU receives voltage signals from various components to detect potential malfunctions within the system.

The variable A/C compressor control circuit includes several components to accomplish this process. Most newer automobiles are equipped with air conditioning, which is an essential element for this circuit to function correctly.

When the engine control unit (ECU) detects abnormally high electrical signals in the variable A/C compressor control circuit, code P06A2 is set, and the check engine light is activated.

P06A2 A/C Compressor

How Severe Is This DTC?

The severity of this code is moderate to severe depending on the specific nature of the problem. While it is a convenient feature for the user, air conditioning malfunctions can progress, leading to extensive repair requirements when not corrected in a timely manner.
What Are Some of the Symptoms of the Code?

Symptoms of a P06A2 fault code may include:

The air conditioner will not work properly
Check engine light illuminated

What Are Some of the Common Causes of the Code?

Causes

of this P06A2 code may include:

Faulty A/C compressor
Faulty A/C solenoid (if applicable)
Undercharged or overcharged system
Clogged orifice tube or dryer
Faulty climate control
Faulty A/C relay
Blown fuse or fusible link (if applicable)
Corroded or damaged connector
Faulty or damaged wiring
Faulty ECU

What Are the Troubleshooting Steps for P06A2?

The first step in the troubleshooting process for any malfunction is to search for technical service bulletins (TSBs) for the specific vehicle by year, model, and powertrain. In some circumstances, this can save you a lot of time in the long run by pointing you in the right direction.

The second step is to locate all components of this circuit and perform a thorough visual inspection to check that the associated wiring does not have obvious defects such as scraping, rubbing, exposed wires, or burn marks. Then, check the connectors for security, corrosion, and damaged pins. This process should include the A/C compressor, associated sensors, relays, and the ECU.
Advanced Steps

Advanced steps become very vehicle-specific and require appropriate advanced equipment to operate accurately. These procedures require a digital multimeter and vehicle-specific technical references. The ideal tool for this troubleshooting process is an A/C diagnostic machine, if available.

This specialized equipment is essential for locating the source of the malfunction by identifying leaks and verifying proper pressures in the system. High and low side gauges will also validate the integrity of the A/C compressor and associated components. Restrictions within the system, such as a clogged orifice tube or dryer, will also be identified. The proper amount of refrigerant in the system also plays a key role in the operation of this circuit. Safety switches, fuses, and fusible links are often incorporated to prevent damage to the A/C compressor.
Voltage Checks

Specific troubleshooting guidelines must be referenced to determine the required voltage ranges for various A/C components. Depending on the configuration, several components are integrated, including the A/C compressor, relays, and solenoids for certain applications. The climate control in newer automobiles can make the troubleshooting process extremely complicated in some cases. Voltage requirements vary depending on the specific year and model of the vehicle.

If this process identifies the absence of a power source or ground, continuity tests may be required to verify the integrity of the wiring, connectors, and other components. Continuity tests should always be performed with the power disconnected from the circuit, and normal readings for wiring and connections should be 0 ohms of resistance. Resistance or lack of continuity is an indication of faulty wiring that is open or shorted and must be repaired or replaced.
What Are the Common Repairs for This Code?

Replacing the A/C compressor
Replacing the A/C solenoid (if applicable)
Replacing the orifice tube or dryer
Replacing the blown fuse or fusible link (if applicable)
Repairing the A/C system leak
Cleaning corrosion from connectors
Repairing or replacing faulty wiring
Evacuating and recharging the system
Flashing or replacing the ECU

Misdiagnosis can lead to replacing the A/C compressor or other associated components when wiring, connectors, or incorrect charge are the cause of the problem.

I hope the information contained in this article has been helpful in guiding you in the right direction to correct the issue with your variable A/C compressor circuit fault code. This article is strictly informational, and the specific technical data and service bulletins for your vehicle should always take priority.

P06A2 Variable A/C Compressor Control Circuit High

What Does It Mean?

This is a generic powertrain diagnostic trouble code (DTC) that applies to many OBD-II vehicles (1996-newer). This may include, but is not limited to, vehicles from General Motors, Honda, Dodge, Ford, BMW, Mercedes, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

OBD-II fault codes P06A0, P06A1, and P06A2 are associated with the variable A/C compressor control circuit.

The purpose of the variable A/C compressor control circuit is to engage and disengage the compressor at the appropriate time to maintain the desired temperature inside the vehicle’s cabin. The ECU receives voltage signals from various components to detect potential malfunctions within the system.

The variable A/C compressor control circuit includes several components to accomplish this process. Most newer automobiles are equipped with air conditioning, which is an essential element for this circuit to function correctly.

When the engine control unit (ECU) detects abnormally high electrical signals in the variable A/C compressor control circuit, code P06A2 is set, and the check engine light is activated.

A Typical A/C Compressor:


P06A2 A/C Compressor
How Severe Is This DTC?

The severity of this code is moderate to severe depending on the specific nature of the problem. While it is a convenient feature for the user, air conditioning malfunctions can progress, leading to significant repair requirements when not corrected in a timely manner.
What Are Some of the Symptoms of the Code?

Symptoms of a P06A2 fault code may include:

The air conditioner will not work properly
Check engine light on

What Are Some Common Causes of the Code?

Causes

of this P06A2 code may include:

Faulty A/C compressor
Faulty A/C solenoid (if applicable)
Undercharged or overcharged system
Clogged orifice tube or dryer
Faulty climate control
Faulty A/C relay
Blown fuse or fusible link (if applicable)
Corroded or damaged connector
Faulty or damaged wiring
Faulty ECU

What Are the P06A2 Troubleshooting Steps?

The first step in the troubleshooting process for any malfunction is to search for technical service bulletins (TSBs) for the specific vehicle by year, model, and powertrain. In some circumstances, this can save a lot of time in the long run by pointing you in the right direction.

The second step is to locate all components of this circuit and perform a thorough visual inspection to check that the associated wiring does not have obvious defects such as scraping, rubbing, exposed wires, or burn marks. Then, check the connectors for security, corrosion, and damaged pins. This process should include the A/C compressor, associated sensors, relays, and the ECU.
Advanced Steps

Advanced steps become very vehicle-specific and require appropriate advanced equipment to function accurately. These procedures require a digital multimeter and vehicle-specific technical references. The ideal tool for this troubleshooting process is an A/C diagnostic machine, if available.

This specialized equipment is essential for locating the source of the malfunction by identifying leaks and verifying proper pressures in the system. High and low side gauges will also validate the integrity of the A/C compressor and associated components. Restrictions within the system, such as a clogged orifice tube or dryer, will also be identified. The proper amount of refrigerant in the system also plays a key role in the operation of this circuit. Safety switches, fuses, and fusible links are often incorporated to prevent damage to the A/C compressor.
Voltage Checks

Specific troubleshooting guidelines must be referenced to determine the required voltage ranges for various A/C components. Depending on the configuration, several components are integrated, including the A/C compressor, relays, and solenoids for certain applications. The climate control in newer automobiles can make the troubleshooting process extremely complicated in some cases. Voltage requirements vary depending on the specific year and model of the vehicle.

If this process identifies the absence of a power source or ground, continuity tests may be required to verify the integrity of the wiring, connectors, and other components. Continuity tests should always be performed with the power disconnected from the circuit, and normal readings for wiring and connections should be 0 ohms of resistance. Resistance or lack of continuity is an indication of faulty wiring that is open or short-circuited and must be repaired or replaced.
What Are the Common Repairs for This Code?

Replacement of the A/C compressor
Replacement of the A/C solenoid (if applicable)
Replacement of the orifice tube or dryer
Replacement of the blown fuse or fusible link (if applicable)
Repairing the A/C system leak
Cleaning corrosion from connectors
Repairing or replacing faulty wiring
Evacuating and recharging the system
Flashing or replacing the ECU

Misdiagnosis can lead to replacing the A/C compressor or other associated components when wiring, connectors, or incorrect charge are the cause of the problem.

I hope the information in this article has been helpful in pointing you in the right direction to correct the issue with your variable A/C compressor control circuit fault code. This article is strictly informational, and the technical data and service bulletins specific to your vehicle should always take priority.

P06A3 Open Sensor D Reference Voltage Circuit

❓ What does the P06A3 code mean?

The P06A3 code is a generic OBD-II code related to the powertrain. It indicates that the PCM (Powertrain Control Module) has detected an open circuit for a sensor identified as “D”.

An “open circuit” means the PCM detects no signal from the sensor in question—it is as if it is absent or disconnected.

This sensor is typically associated with a transmission component, the transfer case, or one of the differentials. Generally, this code appears in addition to another more specific code. If P06A3 appears alone, it may be a software bug in the PCM.

⚠️ Possible symptoms

Symptoms vary depending on the sensor involved, but may include:

  • Inability to switch between Sport and Eco modes,

  • Malfunctions in gear shifting (automatic transmission),

  • Delayed or no transmission engagement,

  • Failure to switch between four-wheel drive (4WD) and two-wheel drive,

  • Inability to change speed ranges (high/low) in the transfer case,

  • Issues with front differential engagement or hubs,

  • Erratic or non-functional speedometer or odometer.

🔍 Possible causes

P06A3 can be caused by:

  • Open circuit in the sensor’s wiring,

  • Disconnected, dirty, or damaged connectors,

  • Blown fuse or faulty relay,

  • Faulty sensor,

  • PCM programming error (rare but possible if no other codes are present).

🛠️ How to diagnose and repair

Required tools:

  • OBD-II scanner,

  • Digital multimeter (DVOM),

  • Wiring diagrams or manufacturer documentation,

  • (Optional) Oscilloscope for testing dynamic sensors.

Recommended steps:

  1. Check other stored codes.

    • P06A3 is often secondary to another sensor code.

    • Address these codes as a priority.

  2. Check fuses and relays.

    • Replace blown fuses,

    • A blown fuse may indicate a short circuit in the circuit.

  3. Inspect the wiring harness.

    • Look for visible damage, cut wires, melted or corroded connectors.

  4. Check voltage at the sensor.

    • The sensor should receive:

      • a reference voltage (5V),

      • a reliable ground,

      • and provide a variable signal to the PCM.

  5. Test the sensor itself.

    • Using the DVOM, measure resistance and continuity,

    • Compare with manufacturer specifications,

    • Replace if out of tolerance.

  6. If needed, use an oscilloscope.

    • This allows real-time observation of the sensor signal,

    • Useful for magnetic or alternating signal sensors.

  7. Clear codes and test drive.

    • If the code does not return after a full cycle, the repair is successful.

🧠 Important notes

  • P06A3 alone is rare; always examine other associated DTCs.

  • The “D” circuit refers to a specific sensor, whose role varies by vehicle. Use technical documentation specific to the make/model to locate it.

P06A4 Low Reference Sensor D Voltage Circuit

What Does It Mean?

This diagnostic trouble code (DTC) is a generic powertrain code, meaning it applies to OBD-II equipped vehicles. Although generic, specific repair steps may vary by make/model.

If your OBD II equipped vehicle has a stored P06A4, it means the powertrain control module (PCM) has detected a low reference voltage signal for a specific sensor designated as “D”. The sensor in question is typically associated with the automatic transmission, transfer case, or one of the differentials.

A more specific sensor code will almost always accompany this code. P06A4 adds that the sensor reference circuit voltage is low. To determine the location (and function) of the sensor regarding the vehicle in question, consult a reliable vehicle information source (All Data DIY is an excellent source). Suspect a PCM programming error if P06A4 is stored alone. You’ll need to diagnose and repair any other sensor codes before diagnosing and repairing P06A4 – but keep the low reference voltage condition in mind.

The sensor in question receives reference voltage (typically five volts) through a switched circuit (powered with ignition on). There will also be a ground signal. The sensor will be of variable resistance or electromagnetic type and will complete the circuit. The sensor’s resistance should decrease as pressure, temperature, or speed increases and vice versa. When the sensor resistance changes (under varying conditions), it provides the PCM with an input voltage signal.

If the input voltage signal received by the PCM is below a programmed threshold, a P06A4 will be stored. A malfunction indicator lamp (MIL) may also illuminate. Some vehicles require multiple drive cycles (with a failure) for the MIL to illuminate. Allow the PCM to enter readiness mode before considering a repair successful. Simply clear the code once repairs are made and drive the vehicle normally. If the PCM enters readiness mode, the repair was successful. If the code resets, the PCM won’t enter readiness mode and you’ll know a malfunction still exists.
Severity and Symptoms

The severity of a stored P06A4 depends on which sensor circuit is experiencing the low voltage condition. Other stored codes must be considered before determining severity.

Symptoms of a P06A4 code may include:

Transmission failure to switch between sport and economy modes
Transmission shifting malfunctions
Delayed (or no) transmission engagement
Transmission failure to switch between four-wheel drive and two-wheel drive modes
Transfer case failure to shift from low to high range
Lack of front differential engagement
Lack of front hub engagement
Erratic or inoperative speedometer/odometer

Causes

Possible causes of this engine code include:

Faulty sensor
Defective or blown fuses and/or fuse links
Faulty system power relay
Open circuits and/or connectors

Diagnostic and Repair Procedures

A diagnostic scanner, digital volt/ohmmeter (DVOM), and reliable vehicle information source (such as All Data DIY) will be needed to diagnose a stored P06A4 code. A portable oscilloscope may also prove useful in your diagnosis.

First, consult your vehicle information source to determine the location and function of the sensor in question regarding your specific vehicle. Perform a visual inspection of wiring harnesses and connectors related to the sensor system. Repair or replace damaged or burned wiring, connectors, and components as needed. Second, connect the scanner to the vehicle’s diagnostic port and retrieve all stored trouble codes and freeze frame data. Document the codes, the order in which they were stored, and any associated freeze frame data, as this information may prove useful if the code proves intermittent. You can now proceed to clear the code; then test drive the vehicle to see if it immediately resets.

If the code immediately resets, use the DVOM to test the reference voltage and ground signals at the sensor in question. You would normally expect to find five volts and ground at the sensor connector.

Continue by testing the sensor’s resistance and continuity levels if voltage and ground signals are present at the sensor connector. Obtain test specifications from your vehicle information source and compare them to your actual results. Sensors not meeting these specifications should be replaced.

Disconnect all associated controllers from system circuits before testing resistance with the DVOM. Failure to do so could result in PCM damage. If reference voltage is low (at the sensor level), use the DVOM to check circuit resistance and continuity between the sensor and PCM. Replace open or shorted circuits as needed. If the sensor in question is electromagnetic with an alternating signal, use the oscilloscope to monitor data. Focus on completely open circuits and issues.

Additional Diagnostic Notes:

This type of code is typically provided as support for a more specific code
A stored P06A4 code is normally associated with the transmission

P06A5 High Sensor D Reference Voltage Circuit

What does it mean?

This diagnostic code (DTC) is a generic powertrain code, meaning it applies to vehicles equipped with OBD-II. Although generic, specific repair steps may vary by make/model.

When faced with a stored P06A5 fault code, I know from experience that the powertrain control module (PCM) has detected a high reference voltage condition for a specific sensor labeled “D”. I recall that the sensor in question has always been related to the automatic transmission, transfer case, or front differential.

An additional sensor code will likely point me in the specific direction of the malfunction, with P06A5 adding that the reference circuit voltage for sensor “D” is too high. To determine the location (and function) of the sensor for the specific vehicle, I would consult a reliable vehicle information source like All Data DIY. If P06A5 was stored alone, I would suspect a PCM programming error occurred. I always diagnose and repair any other sensor codes before addressing P06A5 – keeping in mind the above-normal reference voltage condition – because it will usually disappear once other (more specific) sensor codes are fixed.

I realize the sensor in question is normally powered with a reference voltage signal (typically five volts) through a switched circuit (powered with ignition on) and a ground signal. Experience dictates that the sensor will be either variable resistance or electromagnetic type and will complete the circuit in question. Typically, sensor resistance should decrease as pressure, temperature, or speed increases and vice versa. When the sensor’s resistance level changes (under varying conditions) and the circuit voltage responds; the PCM recognizes voltage variations as changes in pressure, temperature, or speed. If the input voltage signal received by the PCM exceeds a programmed limit, P06A5 will be stored and a malfunction indicator light (MIL) may illuminate. Some models require multiple drive cycles (with failure) for the MIL to illuminate. Good things happen when I allow the PCM to enter readiness mode before considering a repair successful. I clear the code once repairs are made and drive the vehicle normally (before returning it to the customer). If the PCM enters readiness mode, the repair succeeded. If the code resets, the PCM won’t enter readiness mode and I know a malfunction still exists.
Severity and Symptoms

The urgency of a stored P06A5 depends on which sensor circuit is experiencing the high reference voltage condition. Accompanying codes must be considered before determining severity level.

Symptoms of a P06A5 code may include

:    Delayed (or no) transmission engagement
    Transmission failure to switch between sport and economy modes
    Transmission shifting malfunctions
    Transmission failure to switch between four-wheel drive and two-wheel drive modes
    Transfer case failure to shift from low to high range
    Lack of front differential engagement
    Lack of front hub engagement
    Erratic or inoperative speedometer/odometer

Causes

Possible causes of this engine code include:

    Short-circuited circuits and/or connectors
    Faulty sensor
    PCM programming error or defective PCM

Diagnostic and Repair Procedures

Before starting my diagnosis for P06A5, I like to have a diagnostic scanner, digital volt/ohmmeter (DVOM), and reliable vehicle information source (like All Data DIY). I’ve also found a portable oscilloscope can be helpful in this diagnosis.

I would begin by consulting my vehicle information source to determine the sensor’s location and function for the specific vehicle. I would continue by performing a visual inspection of wiring harnesses and connectors related to the sensor circuit. I would repair or replace damaged or burned wiring, connectors, and components as needed.

Next, I like to connect the scanner to the vehicle’s diagnostic port and retrieve all stored fault codes and freeze frame data. I write down the codes, the order they were stored, and any associated freeze frame data, as this information can prove useful if the code proves intermittent. Then I would proceed to clear the codes and test drive the vehicle to see if it resets.

If the code immediately resets, I would use the DVOM to test reference voltage and ground signals at the sensor in question. I would expect to find five volts and ground at the sensor connector.

I would probably continue by testing sensor resistance and continuity levels if voltage and ground signals are present at the sensor connector. I can obtain specifications from my vehicle information source and compare my actual results with them. Sensors not meeting these specifications will need replacement.

I always disconnect all associated controllers from system circuits before testing resistance with the DVOM because I know failure to do so can cause PCM damage. If reference voltage is high (at sensor level), use the DVOM to check circuit resistance and continuity between sensor and PCM. Replace short-circuited circuits as needed.

If the sensor in question is electromagnetic with alternating signal, use the oscilloscope to monitor live data. Focus on spikes, glitches, and maximized circuits.

Additional diagnostic notes:

     This type of code is usually provided as support for a more specific code
     A stored P06A5 code is normally associated with the transmission

P06A6 Sensor A Reference Voltage Circuit Range/Performance

What Does It Mean?

The diagnostic trouble code (DTC) is a generic powertrain code, meaning it applies to vehicles equipped with OBD-II. This can include, but is not limited to, vehicles from Ford, Chevrolet, Honda, etc. Although generic, specific repair steps may vary by make/model.

If your OBD-II vehicle has a stored P06A6 code, it means the Powertrain Control Module (PCM) has detected an out-of-range reference voltage signal or a performance issue with a specific sensor designated as “A.” The sensor in question is typically associated with the automatic transmission, transfer case, or one of the differentials.

A more specific sensor code will almost always accompany this code. P06A6 adds that the sensor’s reference circuit voltage is out of range or not performing as expected. To determine the location and function of sensor “A” for the specific vehicle, consult a reliable vehicle information source (e.g., AllDataDIY). A PCM programming error may be suspected if P06A6 is stored alone. Diagnose and repair any other sensor codes before addressing P06A6—but keep the reference voltage range/performance condition in mind.

The sensor in question is supplied with reference voltage (typically 5 volts) via a switched circuit (powered with the ignition on). There will also be a ground signal. The sensor will be of a variable resistance or electromagnetic type and will complete the circuit. The sensor’s resistance should decrease as pressure, temperature, or speed increases and vice versa. When the sensor’s resistance changes (under varying conditions), it provides the PCM with an input voltage signal.

If the input voltage signal received by the PCM is outside the expected parameters, a P06A6 will be stored. A Malfunction Indicator Lamp (MIL) may also illuminate. Some vehicles require multiple drive cycles (with a fault) for the MIL to turn on. Allow the PCM to enter readiness mode before considering the repair successful. Simply clear the code after repairs and drive the vehicle normally. If the PCM enters readiness mode, the repair was successful. If the code resets, the PCM will not enter readiness mode, indicating a malfunction still exists.
Severity and Symptoms

The severity of this DTC depends on which sensor circuit is experiencing the abnormal voltage situation. Other stored codes must be considered before determining severity.

Symptoms of a P06A6 code may include:

Transmission failure to switch between sport and economy modes
Transmission shifting malfunctions
Delayed (or no) transmission engagement
Transmission failure to switch between all-wheel drive and two-wheel drive modes
Transfer case failure to shift from low to high range
Lack of front differential engagement
Lack of front hub engagement
Erratic or inoperative speedometer/odometer

Causes

Possible causes of this engine code include:

Faulty sensor
Defective or blown fuses and/or fuse links
Faulty system power relay
Open circuits and/or connectors

Diagnostic and Repair Procedures

A diagnostic scanner, digital volt/ohmmeter (DVOM), and a reliable vehicle information source (such as All Data DIY) are necessary to diagnose a stored P06A6 code. A portable oscilloscope may also be useful in your diagnosis.

First, consult your vehicle information source to determine the location and function of the sensor in question for your specific vehicle. Perform a visual inspection of wiring harnesses and connectors related to the sensor system. Repair or replace any damaged or burnt wiring, connectors, and components as needed. Second, connect the scanner to the vehicle’s diagnostic port and retrieve all stored trouble codes and freeze frame data. Note the codes, the order in which they were stored, and any associated freeze frame data, as this information may be useful if the code is intermittent. You can now proceed to clear the code and test the vehicle to see if it immediately resets.

If the code immediately resets, use the DVOM to test the reference voltage and ground signals at the sensor in question. You would normally expect to find 5 volts and a ground at the sensor connector.

Continue by testing the sensor’s resistance and continuity levels if voltage and ground signals are present at the sensor connector. Obtain test specifications from your vehicle information source and compare them to your actual results. Sensors not meeting these specifications should be replaced.

Disconnect all associated controllers from the system circuits before testing resistance with the DVOM. Failure to do so could result in PCM damage. If the reference voltage is low (at the sensor level), use the DVOM to check circuit resistance and continuity between the sensor and the PCM. Replace any open or shorted circuits as necessary. If the sensor in question is electromagnetic with an alternating signal, use the oscilloscope to monitor live data. Focus on issues and completely open circuits.

Additional Diagnostic Notes:

This type of code is usually provided as support for a more specific code
A stored P06A6 code is normally associated with the transmission

P06A7 Reference Range/Performance of Sensor Reference Voltage B Circuit

What Does It Mean?

Diagnostic Trouble Code (DTC)

This diagnostic trouble code (DTC) is a generic powertrain code, meaning it applies to OBD-II equipped vehicles. This may include, but is not limited to, vehicles from Ford, Chevrolet, Honda, etc. Although generic, specific repair steps may vary by make/model.

Meaning of Code P06A7

If your OBD-II vehicle has a stored P06A7 code, it means the Powertrain Control Module (PCM) has detected an out-of-range reference voltage signal or a performance issue with a specific sensor designated as “B”. The sensor in question is typically associated with the automatic transmission, transfer case, or one of the differentials.

A more specific sensor code will almost always accompany this code. P06A7 adds that the sensor’s reference circuit voltage is out of range or not performing as expected.

To determine the location and function of the “B” sensor for the vehicle in question, consult a reliable vehicle information source (e.g., AllDataDIY). Consider a PCM programming error if P06A7 is stored alone. You’ll need to diagnose and repair any other sensor codes before addressing P06A7 – but keep in mind the reference voltage range/performance condition.

Operation of Sensor “B”

The sensor in question is supplied with reference voltage (typically 5 volts) through a switched circuit (powered with the ignition on). There will also be a ground signal.

The sensor will be of variable resistance or electromagnetic type and will complete the circuit. The sensor’s resistance should decrease as pressure, temperature, or speed increases and vice versa. When the sensor’s resistance changes (under varying conditions), it provides the PCM with an input voltage signal.

Symptoms of Code P06A7

The severity of this DTC depends on which sensor circuit is experiencing the abnormal voltage situation. Other stored codes must be considered before determining severity.

Possible Symptoms:

  • Transmission fails to switch between sport and economy modes
  • Transmission shifting malfunctions
  • Delayed (or no) transmission engagement
  • Transmission fails to switch between four-wheel drive and two-wheel drive modes
  • Transfer case fails to shift from low to high range
  • No front differential engagement
  • No front hub engagement
  • Erratic or inoperative speedometer/odometer

Possible Causes

Factors That Can Trigger Code P06A7

  • Faulty sensor
  • Defective or blown fuses and/or fuse links
  • Faulty system power relay
  • Open circuits and/or connectors

Diagnostic and Repair Procedures

Required Tools

A diagnostic scanner, digital volt/ohmmeter (DVOM), and reliable vehicle information source (such as AllDataDIY) will be needed to diagnose a stored P06A7 code. A portable oscilloscope may also prove useful in your diagnosis.

Diagnostic Steps

  1. Consult Information Sources: Determine the location and function of the sensor in question for your vehicle.
  2. Visual Inspection: Examine wiring harnesses and connectors related to the sensor system. Replace damaged components.
  3. Retrieving Error Codes: Connect an OBD-II scanner to the vehicle’s diagnostic port.
  4. Clearing Codes: Clear stored codes and test drive the vehicle.
  5. Checking Voltages: Use the DVOM to test reference voltage and ground signals.
  6. Sensor Testing: If voltage and ground signals are present, test sensor resistance and continuity.
  7. Circuit Check: If reference voltage is low, test circuit resistance and continuity between sensor and PCM.

Additional Diagnostic Notes

  • This type of code is typically provided as support for a more specific code.
  • A stored P06A7 code is normally associated with the transmission.

By following these steps, you’ll be able to effectively diagnose and repair a stored P06A7 code on your vehicle.

P06A8 Sensor C Reference Voltage Circuit Range/Performance

What Does It Mean?

This diagnostic trouble code (DTC) is a generic powertrain code, meaning it applies to OBD-II equipped vehicles. This may include, but is not limited to, vehicles from Ford, Chevrolet, Honda, etc. Although generic, specific repair steps may vary by make/model.

If your OBD-II vehicle has a stored P06A8 code, it means the Powertrain Control Module (PCM) has detected an out-of-range reference voltage signal or a performance issue with a specific sensor designated as “C”. The sensor in question is typically associated with the automatic transmission, transfer case, or one of the differentials.

A more specific sensor code will almost always accompany this code. P06A8 adds that the sensor’s reference circuit voltage is out of range or not performing as expected. To determine the location and function of the “C” sensor for the specific vehicle, consult a reliable vehicle information source (e.g., AllDataDIY). Consider a PCM programming error if P06A8 is stored alone. You’ll need to diagnose and repair any other sensor codes before addressing P06A8—but keep in mind the reference voltage range/performance condition.

The sensor in question is supplied with reference voltage (typically 5 volts) through a switched circuit (powered with the key on). There will also be a ground signal. The sensor will be of variable resistance or electromagnetic type and will complete the circuit. The sensor’s resistance should decrease as pressure, temperature, or speed increases, and vice versa. When the sensor’s resistance changes (under varying conditions), it provides the PCM with an input voltage signal.

Example PCM Photo:


P06A8 PCM

If the input voltage signal received by the PCM is outside expected parameters, a P06A8 will be stored. A Malfunction Indicator Lamp (MIL) may also illuminate. Some vehicles require multiple drive cycles (with a failure) for the MIL to turn on. Allow the PCM to enter readiness mode before considering a repair successful. Simply clear the code once repairs are made and drive the vehicle normally. If the PCM enters readiness mode, the repair was successful. If the code resets, the PCM won’t enter readiness mode, indicating a malfunction still exists.
Severity and Symptoms

The severity of this DTC depends on which sensor circuit is experiencing the abnormal voltage situation. Other stored codes must be considered before determining severity.

Symptoms of a P06A8 code may include:

Transmission failure to switch between sport and economy modes
Transmission shifting malfunctions
Delayed (or no) transmission engagement
Transmission failure to switch between 4WD and 2WD modes
Transfer case failure to shift from low to high range
Lack of front differential engagement
Lack of front hub engagement
Erratic or inoperative speedometer/odometer

Causes

Possible causes of this engine code include:

Faulty sensor
Defective or blown fuses and/or fusible links
Faulty system power relay
Open circuits and/or connectors

Diagnostic and Repair Procedures

A diagnostic scanner, digital volt/ohmmeter (DVOM), and reliable vehicle information source (like All Data DIY) will be needed to diagnose a stored P06A8 code. A portable oscilloscope may also prove useful in your diagnosis.

First, consult your vehicle information source to determine the location and function of the sensor in question for your specific vehicle. Perform a visual inspection of wiring harnesses and connectors related to the sensor system. Repair or replace damaged or burned wiring, connectors, and components as needed. Second, connect the scanner to the vehicle’s diagnostic port and retrieve all stored trouble codes and freeze frame data. Note the codes, the order in which they were stored, and any associated freeze frame data, as this information may prove useful if the code proves intermittent. You can now proceed to clear the code; then test drive the vehicle to see if it immediately resets.

If the code immediately resets, use the DVOM to test the reference voltage and ground signals at the sensor in question. You would normally expect to find 5 volts and ground at the sensor connector.

Continue by testing the sensor’s resistance and continuity levels if voltage and ground signals are present at the sensor connector. Obtain testing specifications from your vehicle information source and compare them to your actual results. Sensors not meeting these specifications should be replaced.

Disconnect all associated controllers from system circuits before testing resistance with the DVOM. Failure to do so could result in PCM damage. If reference voltage is low (at the sensor), use the DVOM to check circuit resistance and continuity between the sensor and PCM. Replace open or shorted circuits as needed. If the sensor in question is electromagnetic with an alternating signal, use the oscilloscope to monitor live data. Focus on issues and completely open circuits.

Additional Diagnostic Notes:

This type of code is typically provided as support for a more specific code
A stored P06A8 code is normally associated with the transmission

P06A9 Sensor D Reference Voltage Circuit Range/Performance

What does it mean?

This diagnostic trouble code (DTC) is a generic powertrain code, meaning it applies to OBD-II equipped vehicles. This may include, but is not limited to, vehicles from Ford, Chevrolet, Honda, etc. Although generic, specific repair steps may vary by make/model.

If your OBD-II vehicle has a stored P06A9 code, it means the Powertrain Control Module (PCM) has detected an out-of-range reference voltage signal or a performance issue with a specific sensor designated as “D”. The sensor in question is typically associated with the automatic transmission, transfer case, or one of the differentials.

A more specific sensor code will almost always accompany this code. P06A9 adds that the sensor’s reference circuit voltage is out of range or not performing as expected. To determine the location and function of sensor “D” for the specific vehicle, consult a reliable vehicle information source (e.g., AllDataDIY). Consider a PCM programming error if P06A9 is stored alone. You’ll need to diagnose and repair any other sensor codes before addressing P06A9 – but keep in mind the reference voltage range/performance condition.

The sensor in question is supplied with reference voltage (typically 5 volts) through a switched circuit (powered with the ignition on). There will also be a ground signal. The sensor will be of variable resistance or electromagnetic type and will complete the circuit. The sensor’s resistance should decrease as pressure, temperature, or speed increases and vice versa. When the sensor’s resistance changes (under varying conditions), it provides the PCM with an input voltage signal.

Example photo of a PCM:


P06A9 PCM

If the input voltage signal received by the PCM is outside expected parameters, a P06A9 will be stored. A Malfunction Indicator Lamp (MIL) may also illuminate. Some vehicles require multiple drive cycles (with a failure) for the MIL to illuminate. Allow the PCM to enter readiness mode before considering a repair successful. Simply clear the code once repairs are made and drive the vehicle normally. If the PCM enters readiness mode, the repair was successful. If the code resets, the PCM won’t enter readiness mode, indicating a malfunction still exists.
Severity and Symptoms

The severity of this DTC depends on which sensor circuit is experiencing the abnormal voltage situation. Other stored codes must be considered before determining severity.

Symptoms of a P06A9 code may include:

Transmission failure to switch between sport and economy modes
Transmission shifting malfunctions
Delayed (or no) transmission engagement
Transmission failure to switch between 4WD and 2WD modes
Transfer case failure to shift from low to high range
Lack of front differential engagement
Lack of front hub engagement
Erratic or inoperative speedometer/odometer

Causes

Possible causes of this engine code include:

Faulty sensor
Defective or blown fuses and/or fuse links
Faulty system power relay
Open circuits and/or connectors

Diagnostic and Repair Procedures

A diagnostic scanner, digital volt/ohmmeter (DVOM), and reliable vehicle information source (like All Data DIY) will be needed to diagnose a stored P06A9 code. A portable oscilloscope may also prove useful in your diagnosis.

First, consult your vehicle information source to determine the location and function of the sensor in question for your specific vehicle. Perform a visual inspection of wiring harnesses and connectors related to the sensor system. Repair or replace damaged or burned wiring, connectors, and components as needed. Second, connect the scanner to the vehicle’s diagnostic port and retrieve all stored trouble codes and freeze frame data. Document the codes, their storage order, and any associated freeze frame data, as this information may prove useful if the code proves intermittent. You can now proceed to clear the code; then test drive the vehicle to see if it immediately resets.

If the code immediately resets, use the DVOM to test reference voltage and ground signals at the sensor in question. You would normally expect to find 5 volts and ground at the sensor connector.

Continue by testing sensor resistance and continuity levels if voltage and ground signals are present at the sensor connector. Obtain test specifications from your vehicle information source and compare them with your actual results. Sensors not meeting these specifications should be replaced.

Disconnect all associated controllers from system circuits before testing resistance with the DVOM. Failure to do so could result in PCM damage. If reference voltage is low (at the sensor level), use the DVOM to check circuit resistance and continuity between the sensor and PCM. Replace open or shorted circuits as needed. If the sensor in question is electromagnetic with an alternating signal, use the oscilloscope to monitor live data. Focus on issues and completely open circuits.

Additional diagnostic notes:

This type of code is typically provided as support for a more specific code
A stored P06A9 code is normally associated with the transmission