P0800 Transfer Case Control System, Indicator Lamp Control

What does it mean?

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

If your vehicle has stored a P0800 code, it means that the powertrain control module (PCM) has received a data input signal indicating that the transfer case control system (TCCS) has detected a malfunction requiring the malfunction indicator lamp (MIL) to illuminate. This type of code applies only to four-wheel drive or all-wheel drive vehicles.

The TCCS and transmission control module (TCM) may be standalone units but are most often integrated into a single housing with the engine control module (ECM). This is referred to as the PCM.

The PCM uses input signals from various engine, transmission, and transfer case sensors to calculate the automatic transmission shift strategy. The transfer case bolts onto the transmission output shaft housing. It is responsible for transferring engine power to the rear differential and front differential, respectively. The transmission output shaft provides power to the transfer case, which can be manipulated to transfer power to the front or rear driveshafts (or both).

The transfer case also contains a selection of gear ranges that typically include 2HI, 4HI, 4LO, and NEUTRAL. Just like power distribution, the transfer case gear range can be selected by pressing a button and controlled electronically (via the TCCS/PCM). Other vehicles must be shifted manually. Vehicles with manually shifted transfer cases typically do not set this type of code.

As with many other transfer case/automatic transmission malfunctions, a transfer case control code can be caused by an electrical or mechanical failure. If the PCM detects that a TCCS malfunction has occurred, a P0800 may be stored and a malfunction indicator lamp (MIL) will illuminate.

How severe is this DTC?

A stored P0800 code indicates that a potentially serious TCCS malfunction has been detected. The conditions that contributed to storing a code of this nature should be rectified as soon as possible.
What are some of the symptoms of the code?

Symptoms of a P0800 fault code may include:

Inability to switch between 2WD and 4WD
Inability to switch between transfer case gear ranges
Flashing or constantly illuminated four-wheel drive or traction control indicator
Unusual noises from the transfer case or driveshaft

What are some common causes of the code?

Causes

of this code may include:

Faulty TCCS actuator or sensor
Internal (mechanical) failure of the transfer case
Shorts or opens in TCCS circuits
Faulty PCM or programming error

What are the troubleshooting steps for P0800?

When diagnosing TCCS codes, you should start by ensuring the fluid is clean and the transfer case is filled to the proper level. If the fluid level is low, locate the source of the leak and repair the condition. Refill the transfer case with the recommended fluid and proceed.

A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information will be needed to diagnose a P0800 code.

You can use your vehicle information source to locate a technical service bulletin (TSB) that matches the vehicle’s year, make, and model; as well as engine size, stored codes, and presented symptoms. If you find one, it may provide helpful diagnostic information.

With the transfer case filled to the proper level with the recommended fluid, move on to the first diagnostic step.

Step 1

Use the scanner (connected to the vehicle’s diagnostic connector) to retrieve all stored codes and relevant freeze frame data. It is a good idea to record this information before clearing the codes, then test drive the vehicle until the PCM enters readiness mode or the code resets.

If the PCM enters readiness mode at this point, the code is intermittent and may be much more difficult to diagnose. If this is the case, the conditions that contributed to storing the code may need to worsen before an accurate diagnosis can be made.

Step 2

If the code immediately resets, the next step in your diagnosis will require you to search your vehicle information source for diagnostic flowcharts, connector pinout charts, connector face views, and component testing procedures/specifications.

Step 3

Use the DVOM to test the voltage and ground circuits at the TCCS controller. If voltage and ground are detected, use the DVOM to check the controller’s output. Begin testing components and sensors related to specific symptoms. Any component not meeting recommended specifications should be considered faulty.

Step 4

If no TCCS components have failed, use the DVOM to test the system circuits. The voltage drop testing method works well for this task. Disconnect all controllers from the circuit before testing resistance with the DVOM.

TCCS-related codes are frequently attributed to the selector
In most cases, transfer case leaks are related to faulty seals

P0801 Reverse Inhibit Control Circuit Malfunction

What does it mean?

This diagnostic trouble code (DTC) is a generic powertrain code and applies to many OBD-II vehicles (1996-newer). This may include, but is not limited to, vehicles from Subaru, Dodge, Buick, Cadillac, Peugeot, Chevrolet, Toyota, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

If your vehicle has stored a P0801 code, it means that the powertrain control module (PCM) has detected a malfunction in the reverse inhibit control circuit. A P0801 may pertain to the transmission or transfer case, depending on the vehicle’s make and model.

The transmission control module (TCM) or transfer case control module (TCCM) may be a standalone unit but is most often integrated into a single housing with the engine control module (ECM). This is referred to as the PCM.

The PCM uses input signals from multiple engine and transmission sensors to calculate the automatic shift strategy. The reverse inhibit switch is designed to prevent the transmission from shifting into reverse while the vehicle is moving forward. Typically, an electronically controlled solenoid is responsible for actuating a piston that prevents the reverse shift lever pawl from engaging the reverse selector when the transmission is already engaged in a forward gear.

If the PCM detects a reverse inhibit circuit voltage level that exceeds the maximum allowable parameters, a P0801 code may be stored and a malfunction indicator lamp (MIL) illuminated.

How severe is this DTC?

The presence of a stored P0801 code indicates that the reverse inhibitor may be disabled. Conditions that contributed to the storage of a code of this nature should be rectified as soon as possible.
What are some of the symptoms of the code?

Symptoms of a P0801 trouble code may include:

The shift lever may engage reverse while the vehicle is moving forward
The shift lever may not engage reverse
There may be no symptoms
Blown fuses in transmission control-related circuits

What are some common causes of the code?

Causes

of this code may include:

Faulty reverse inhibit solenoid
Bad reverse inhibit sensor
Open or shorted reverse inhibit control circuit
Faulty PCM or programming error

What are the troubleshooting steps for P0801?

When diagnosing automatic transmission codes, you should start by ensuring the transmission fluid is clean and the transmission is filled to the appropriate level. If the fluid level is low, locate the source of the leak and repair the condition. Refill the transmission with the recommended fluid and proceed.

A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information will be needed to diagnose a P0801 code.

With the transmission filled to the proper level with the recommended fluid, move on to the first step of diagnosis.

Step 1

Use the scanner (connected to the vehicle’s diagnostic connector) to retrieve all stored codes and relevant freeze frame data. It’s a good idea to record this information before clearing the codes, then test-drive the vehicle until the PCM enters readiness mode or the code resets.

If the PCM enters readiness mode at this point, the code is intermittent and may be much more difficult to diagnose. If this is the case, the conditions that contributed to the code storage may need to worsen before an accurate diagnosis can be made.

Step 2

If the code immediately resets, the next step in your diagnosis will require you to search your vehicle information source for diagnostic flowcharts, connector pinout diagrams, connector face views, and component testing procedures/specifications.

Step 3

Use the DVOM to test voltage and ground circuits at the reverse inhibit solenoid and sensor (if applicable). If voltage and ground are present, test the reverse inhibit solenoid and sensor according to manufacturer specifications. Any component not meeting recommended specifications should be considered faulty. If the components are functional, test the signal circuit that enters the PCM.

Step 4

If the reverse inhibit solenoid and sensor are functional and the signal input is present, use the DVOM to test the system circuits. The voltage drop testing method works well for this task. Disconnect all controllers from the circuit before testing resistance with the DVOM.

Worn shift linkage, worn shift fork, or worn control pawl can contribute to reverse control failure

P0802 Transmission Control System / Open

1. What is the P0802 Code?

The Diagnostic Trouble Code (DTC) P0802 is a generic powertrain code applicable to many OBD-II vehicles (1996 and newer), including Chevrolet, Kia, GMC, Dodge, Ford, Ram, etc.

This code indicates that the Powertrain Control Module (PCM) has received a signal from the Transmission Control System (TCS) reporting a malfunction that requires the Malfunction Indicator Lamp (MIL) to be illuminated.

2. Transmission System Operation

The Transmission Control Module (TCM) can be a standalone unit or integrated into the Engine Control Module (ECM), forming the PCM.

The PCM regulates the transmission using various sensors to control the hydraulic fluid and pressure needed for shifting gears. It relies particularly on:

Electronic Pressure Control (EPC) Solenoids: Regulate fluid pressure.
Electronic Pressure (EP) Sensors: Provide information on fluid pressure.
Electronic Shift Solenoids: Control fluid flow to allow gear changes.
Transmission Input and Output Speed Sensors: Verify the effectiveness of gear shifting.

3. Severity of the P0802 Code

A P0802 code indicates a potentially serious issue with the TCS. It is recommended to diagnose and repair the fault quickly to avoid further damage to the transmission.

4. Symptoms of the P0802 Code

Possible symptoms include:
✅ Irregular or harsh shifting
✅ Delayed or no gear engagement
✅ Transmission entering “limp mode”

5. Common Causes of the P0802 Code

Possible causes include:
🔴 A faulty PCM or TCM module
🔴 Open or shorted transmission control circuits
🔴 Controller programming error

6. Troubleshooting Steps for the P0802 Code

🔍 Step 1: Checking Transmission Fluid

✔️ Ensure the transmission fluid is clean and at the proper level.
✔️ If there is a leak, locate and repair it before refilling with the recommended fluid.
✔️ If the fluid is dark and smells burnt, it should be replaced (drain and filter change recommended).

🔍 Step 2: Using an OBD-II Scanner

✔️ Connect an OBD-II scanner to retrieve stored codes and freeze frame data.
✔️ Note this information before clearing the codes.
✔️ Perform a road test to see if the code resets.

🔍 Step 3: Analyzing Circuits and Sensors

✔️ Consult the vehicle’s electrical diagrams to identify TCM/PCM connections.
✔️ Check voltages and grounds at the TCM/PCM using a digital voltmeter (DVOM).
✔️ Test components involved in the observed symptoms.

🔍 Step 4: Checking Fuses and Circuits

✔️ Test TCM/PCM circuit fuses under load to avoid diagnostic errors.
✔️ Check circuit resistance by disconnecting controllers before testing with the DVOM.

P0803 1-4 Shift Solenoid Control Circuit Malfunction

What does it mean?

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

If your vehicle has stored a P0803 code, it means that the Powertrain Control Module (PCM) has detected a malfunction in the transmission shift solenoid control system (also known as skip shift).

The automatic transmission shift control solenoid is used in vehicle applications where the transmission can be manually shifted through the gear range by pushing or pulling the shift lever in a single direction. This feature is particularly appreciated in high-performance or sports cars. Since the shift lever only needs to be moved slightly, an electronic solenoid is required to input a shift signal into the TCM and perform the desired gear change.

The Transmission Control Module (TCM) can be a standalone unit but is most often integrated into a single housing with the Engine Control Module (ECM). This is referred to as the PCM.

If the PCM detects a malfunction in the upshift solenoid control circuit, a P0803 code will be stored and a Malfunction Indicator Lamp (MIL) will illuminate.

How severe is this DTC?

A stored P0803 code indicates that a malfunction in the upshift solenoid control circuit has been detected. Since the upshift (or skip shift) system is an auxiliary or high-performance shifting function, it is not a critical transmission control system, and a P0803 code should not be classified as severe.
What are some of the symptoms of the code?

Symptoms of a P0803 fault code may include:

    Skip shift is partially or fully disabled
    The skip shift indicator light is on or flashing
    The transmission may be placed in limp mode

What are some common causes of the code?

Causes

of this code may include:

    Faulty shift solenoid
    Shorted or open shift solenoid control wiring or connectors
    Controller programming error

What are the troubleshooting steps for P0803?

When diagnosing automatic transmission codes, you should start by ensuring the transmission fluid is clean and the transmission is filled to the proper level. If the fluid level is low, locate the source of the leak and repair the condition. Refill the transmission with the recommended fluid and proceed.

If the fluid is excessively dark and has a strong burnt friction material smell, it will need to be replaced. To do this, remove the transmission pan (and drain the torque converter) or flush the transmission (recommended). In either case, you will also want to replace the filter at this time. When removing the transmission pan, be sure to save any debris that may have landed in it. If the pan is relatively free of debris, you can assume the clutches are mechanically intact. If there is an excessive amount of friction material in the pan (and stuck to the magnet), the transmission will require rebuilding by a qualified technician.

A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information will be required to diagnose a P0803 code.

You can use your vehicle information source to locate a Technical Service Bulletin (TSB) that matches the vehicle’s year, make, and model; as well as the engine size, stored codes, and presented symptoms. If you find one, it may provide useful diagnostic information.

With the transmission filled to the proper level with the recommended fluid, proceed to the first step of diagnosis.

Step 1

If the PCM enters readiness mode at this point, the code is intermittent and may be much more difficult to diagnose. If this is the case, the conditions that contributed to the code being stored may need to worsen before an accurate diagnosis can be made.

Step 2

If the code resets immediately, the next step in your diagnosis will require you to search your vehicle information source for diagnostic flowcharts, connector pinout diagrams, connector face views, and component testing procedures/specifications.

Step 3

Use the DVOM to test the voltage and ground circuits at the shift solenoid. If voltage and ground are detected, use the DVOM to test the solenoid itself.

Step 4

If no skip shift component has failed, use the DVOM to test the system circuits. The voltage drop testing method works well for this task. Disconnect all controllers from the circuit before testing resistance with the DVOM.

Test the shift control circuit fuses with the circuit loaded to avoid misdiagnosis

P0804 1-4 Upshift (Skip Shift) Control Circuit Malfunction

What does it mean?

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

If your vehicle has stored a P0804 code, it means that the Powertrain Control Module (PCM) has detected a malfunction in the shift lamp control system (also known as skip shift).

The automatic transmission shift control solenoid is used in vehicle applications where the transmission can be manually shifted within the gear range by pushing or pulling the gear lever in a single direction. This feature is particularly appreciated in high-performance or sports cars. Since the gear lever only needs to be moved slightly, an electronic solenoid is required to input a shift signal into the TCM and perform the desired gear shift. The shift indicator light illuminates when the driver selects the shift function as opposed to the conventional automatic gear lever. It may also be illuminated (or flash) if a problem is detected.

The Transmission Control Module (TCM) can be a standalone unit but is most often integrated into a single housing with the Engine Control Module (ECM). This is referred to as the PCM.

If the PCM detects a malfunction in the shift lamp control circuit, a P0804 code will be stored and a Malfunction Indicator Lamp (MIL) will illuminate.

How severe is this DTC?

A stored P0804 code indicates that a malfunction in the shift lamp control circuit has been detected. Since the upshift (or skip shift) system is an auxiliary or high-performance shifting function, it is not a critical transmission control system, and a P0804 code should not be classified as severe.
What are some of the symptoms of the code?

Symptoms of a P0804 fault code may include:

    Skip shift is partially or fully disabled
    The skip shift indicator light is inoperative, illuminated, or flashing
    The transmission may be placed in limp mode

What are some common causes of the code?

Causes

of this code may include:

    Faulty shift lamp bulb
    Shorted or open shift lamp control wiring or connectors
    Controller programming error

What are the troubleshooting steps for P0804?

A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information will be necessary to diagnose a P0804 code.

You can use your vehicle information source to locate a Technical Service Bulletin (TSB) that matches the vehicle’s year, make, and model; as well as engine size, stored codes, and presented symptoms. If you find one, it may provide useful diagnostic information.

With the transmission filled to the proper level with the recommended fluid, proceed to the first step of diagnosis.

Step 1

Step 2

Step 3

Use the DVOM to test the voltage and ground circuits at the shift indicator light. If voltage and ground are detected, use the DVOM to test the lamp bulb.

Step 4

Test the skip shift fuse system with the circuit loaded to avoid misdiagnosis

Clutch Position Sensor Circuit P0805

Meaning of Code P0805

P0805 is a generic OBD-II code indicating a malfunction in the clutch position sensor circuit. This issue primarily affects vehicles with manual transmissions and can involve various brands:

Dodge, Ford, Chevrolet, Jeep
Toyota, Mercedes, Land Rover, Smart

The control module (PCM or TCM) monitors this circuit to ensure the clutch is fully depressed before the engine starts.

Severity of the Problem

Moderate: The vehicle can usually be driven, but…
Serious if the engine starts without pressing the clutch (safety risk)

Common Symptoms

🚗 Engine does not start
⚠️ Check engine or transmission light on
🔥 Engine starts even without the clutch pressed

Possible Causes

Faulty clutch sensor
Wiring issues (short circuits, damaged wires)
Oxidized or loose connectors
Grounding problem
Faulty PCM/TCM (less common)

Diagnostic Procedure

Step 1: Check Technical Bulletins

🔍 Consult the TSBs (Technical Service Bulletins) for your specific model.

Step 2: Visual Inspection

Locate the clutch sensor (usually near the pedal)
Check wires and connectors for:
- Corrosion
- Exposed wires
- Physical damage

Step 3: Electrical Tests

Using a multimeter:

Voltage test:
- Clutch released: 12V on one side of the sensor
- Clutch pressed: voltage on both sides
Continuity test:
- Check for no breaks in the cables
- Verify ground connections

Common Repairs

🔧 Clean corroded connectors
🔌 Replace damaged cables
🔋 Change the clutch sensor if faulty
💻 Update/reprogram the PCM if necessary

Common Mistake to Avoid

⚠️ Do not unnecessarily replace the starter or PCM before checking the sensor and its wiring!

Conclusion

Code P0805 usually indicates a simple issue (wiring or sensor), but requires precise diagnosis. If you are not comfortable with electrical tests, consult a professional.

🔧 Tip: Always use technical data specific to your vehicle for accurate diagnosis.

P0806 Clutch Position Sensor Circuit Range / Performance

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 Dodge, Ford, Smart, Land Rover, Chevrolet, Chrysler, Jeep, Mercedes, Toyota, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

The OBD-II fault code P0806 and related codes P0805, P0807, P0808, P0809, and P080A are associated with the clutch position sensor circuit. This circuit is monitored by the Powertrain Control Module (PCM) or the Transmission Control Module (TCM) depending on the specific vehicle.

The purpose of the clutch position sensor circuit is to monitor the status of the clutch on a manual transmission. This process is accomplished by reading the output voltage from the clutch position sensor which indicates when the clutch is engaged. In most cases, the clutch position sensor is typically a basic on/off switch mounted near the clutch pedal on the bracket. A constant voltage is usually present on one side of the switch and the contacts are closed by engaging the clutch, transferring the voltage to the starter or starter solenoid. This basic circuit and switch prevent the engine from starting before the clutch is engaged.

When the PCM or TCM detects a voltage or resistance in the clutch position sensor circuit that is outside the expected range or another performance issue, code P0806 will be set and the check engine light or transmission warning light will illuminate.

A clutch position sensor:
P0806 Clutch Position Sensor
How severe is this DTC?

The severity of this code is normally moderate, but P0806 can be severe if the vehicle starts with the clutch disengaged, creating a safety issue.
What are some of the symptoms of the code?

Symptoms of a P0806 fault code may include:

Engine does not start
Engine starts without engaging the clutch
Transmission warning light on
Check engine light on

What are some of the common causes of the code?

Causes

of this P0806 code may include:

Faulty clutch position sensor
Defective or damaged wiring
Loose or faulty control module ground strap
Corroded, damaged, or loose connector
Blown fuse or fusible link (if applicable)
Faulty PCM or TCM

What are the troubleshooting steps for P0806?

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 the clutch position sensor switch and look for obvious physical damage. Perform a thorough visual inspection to check that the associated wiring does not have obvious defects such as scraping, rubbing, bare wires, or burn marks. Then, check the connectors and connections for security, corrosion, and damaged pins. This process should include all wiring connectors and connections to the clutch position sensor switch, PCM, starter, and starter solenoid. Consult vehicle-specific technical data to see if a fuse or fusible link is incorporated into the circuit.
Advanced Steps

Advanced steps become very vehicle-specific and require appropriate advanced equipment to perform accurately. These procedures require a digital multimeter and vehicle-specific technical references. The specific technical data will include troubleshooting charts and the proper sequence to follow to help you make an accurate diagnosis.
Voltage Checks

When the clutch is disengaged, there should be proper 12 volts on one side of the sensor. When the clutch is engaged, you should have voltage on both sides of the sensor. The starter solenoid or starter should also be powered depending on the configuration.

If this process identifies a missing power source or ground, continuity tests may be required to check 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. A continuity test between the PCM or TCM control and the chassis will confirm the service level of the ground straps and wires. The presence of resistance indicates a loose connection or possible corrosion.
What are the common repairs for this code?

Cleaning corrosion from connectors
Repairing or replacing faulty wiring
Replacing a blown fuse or fusible link (if applicable)
Repairing or replacing faulty ground straps
Reprogramming or replacing the PCM or TCM

Common Mistake

Replacing the starter, starter solenoid, or a control module when the clutch position sensor or damaged wiring is causing this issue.

I hope the information in this article has been helpful in guiding you in the right direction to fix the issue with your clutch position sensor circuit error code. This article is strictly informational, and the technical data and service bulletins specific to your vehicle should always take priority.

Low Clutch Position Sensor Circuit P0807

What Does It Mean?

The OBD-II fault code P0807 and related codes P0805, P0806, P0808, P0809, and P080A are associated with the clutch position sensor circuit. This circuit is monitored by the Powertrain Control Module (PCM) or the Transmission Control Module (TCM) depending on the specific vehicle.

The purpose of the clutch position sensor circuit is to monitor the status of the clutch on a manual transmission. This process is accomplished by reading the output voltage from the clutch position sensor, which indicates when the clutch is engaged. In most cases, the clutch position sensor is typically a basic on/off switch mounted near the clutch pedal on the bracket. A constant voltage is usually present on one side of the switch, and the contacts are closed by engaging the clutch, transferring the voltage to the starter or starter solenoid. This basic circuit and switch prevent the engine from starting before the clutch is engaged.

When the PCM or TCM detects a voltage or resistance lower than expected in the clutch position sensor circuit, code P0807 is set, and the Check Engine light or Transmission Warning light illuminates.

How Severe Is This DTC?

The severity of this code is normally moderate, but P0807 can be severe if the vehicle starts with the clutch disengaged, creating a safety issue.
What Are Some of the Symptoms of the Code?

Symptoms of a P0807 fault code may include:

Engine does not start
Engine starts without engaging the clutch
Transmission Warning light on
Check Engine light on

What Are Some Common Causes of the Code?

Causes

of this P0807 code may include:

What Are the P0807 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 the clutch position sensor switch and look for obvious physical damage. Perform a thorough visual inspection to check that the associated wiring has no obvious defects such as scraping, rubbing, bare wires, or burn marks. Then, check the connectors and connections for security, corrosion, and damaged pins. This process should include all wiring connectors and connections to the clutch position sensor switch, PCM, starter, and starter solenoid. Consult vehicle-specific technical data to see if a fuse or fusible link is incorporated into the circuit.
Advanced Steps

If this process identifies the absence of a power source or ground, continuity tests may be required to check 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. A continuity test between the PCM or TCM control and the chassis will confirm the service level of the ground straps and wires. The presence of resistance indicates a loose connection or possible corrosion.
What Are the Common Repairs for This Code?

Common Mistake

Replacing the starter, starter solenoid, or a control module when the clutch position sensor or damaged wiring is the problem.

I hope the information in this article has been helpful in guiding you in the right direction to correct the issue with your clutch position sensor circuit error code. This article is strictly informational, and the technical data and service bulletins specific to your vehicle should always take priority.

P0808 High Clutch Position Sensor Circuit

What Does It Mean?

The OBD-II fault code P0808 and related codes P0805, P0806, P0807, P0809, and P080A are associated with the clutch position sensor circuit. This circuit is monitored by the Powertrain Control Module (PCM) or the Transmission Control Module (TCM), depending on the specific vehicle.

The purpose of the clutch position sensor circuit is to monitor the status of the clutch on a manual transmission. This process is accomplished by reading the output voltage from the clutch position sensor, which indicates when the clutch is engaged. In most cases, the clutch position sensor is typically a basic on/off switch mounted near the clutch pedal on the bracket. A constant voltage is usually present on one side of the switch, and the contacts are closed when the clutch is engaged, transferring the voltage to the starter or starter solenoid. This basic circuit and switch prevent the engine from starting before the clutch is engaged.

When the PCM or TCM detects a higher voltage or resistance than expected in the clutch position sensor circuit, code P0808 will be set, and the check engine light or transmission warning light will illuminate.

How Severe Is This DTC?

The severity of this code is normally moderate, but P0808 can be serious if the vehicle starts with the clutch disengaged, creating a safety issue.
What Are Some of the Symptoms of the Code?

Symptoms of a P0808 fault code may include:

Engine does not start
Engine starts without engaging the clutch
Transmission warning light illuminated
Check engine light illuminated

What Are Some Common Causes of the Code?

Causes

of this P0808 code may include:

What Are the Troubleshooting Steps for P0808?

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 the clutch position sensor switch and look for obvious physical damage. 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 and connections for security, corrosion, and damaged pins. This process should include all wiring connectors and connections to the clutch position sensor switch, PCM, starter, and starter solenoid. Refer to vehicle-specific technical data to see if a fuse or fusible link is incorporated into the circuit.
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 specific technical data will include troubleshooting charts and the proper sequence to follow to help you make an accurate diagnosis.
Voltage Checks

If this process identifies a missing power source or ground, continuity tests may be required to check 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 indicates faulty wiring that is open or shorted and must be repaired or replaced. A continuity test between the PCM or TCM control and the chassis will confirm the service level of the ground straps and wires. The presence of resistance indicates a loose connection or possible corrosion.
What Are the Common Repairs for This Code?

Common Mistake

Replacing the starter, starter solenoid, or a control module when a faulty clutch position sensor or damaged wiring is causing this issue.

P0809 Intermittent Clutch Position Sensor Circuit

What does it mean?

The OBD-II fault code P0809 and related codes P0805, P0806, P0807, P0808, and P080A are associated with the clutch position sensor circuit. This circuit is monitored by the Powertrain Control Module (PCM) or the Transmission Control Module (TCM) depending on the specific vehicle.

The purpose of the clutch position sensor circuit is to monitor the status of the clutch on a manual transmission. This process is accomplished by reading the output voltage from the clutch position sensor, which indicates when the clutch is engaged. In most cases, the clutch position sensor is typically a basic on/off switch mounted near the clutch pedal on the bracket. A constant voltage is usually present on one side of the switch, and the contacts are closed by engaging the clutch, transferring the voltage to the starter or starter solenoid. This basic circuit and switch prevent the engine from starting before the clutch is engaged.

When the PCM or TCM detects an intermittent voltage or resistance problem in the clutch position sensor circuit, code P0809 is set, and the check engine light or transmission warning light illuminates.

How severe is this DTC?

The severity of this code is normally moderate, but P0809 can be serious if the vehicle starts with the clutch disengaged, creating a safety issue.
What are some of the symptoms of the code?

Symptoms of a P0809 fault code may include:

Engine does not start
Engine starts without engaging the clutch
Transmission warning light on
Check engine light on

What are some common causes of the code?

Causes

of this P0809 code may include:

What are the troubleshooting steps for P0809?

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 the clutch position sensor switch and look for obvious physical damage. 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 and connections for security, corrosion, and damaged pins. This process should include all wiring connectors and connections to the clutch position sensor switch, PCM, starter, and starter solenoid. Consult vehicle-specific technical data to see if a fuse or fusible link is incorporated into the circuit.
Advanced Steps

Advanced steps become very vehicle-specific and require appropriate advanced equipment to perform accurately. These procedures require a digital multimeter and the vehicle-specific technical references. The specific technical data will include troubleshooting charts and the proper sequence to follow to help you make an accurate diagnosis.
Voltage Checks

If this process identifies a missing power source or ground, continuity tests may be required to check 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. A continuity test between the PCM or TCM control and the chassis will confirm the serviceability of the ground straps and wires. The presence of resistance indicates a loose connection or possible corrosion.
What are the common repairs for this code?

Common Mistake

Replacing the starter, starter solenoid, or a control module when a faulty clutch position sensor or damaged wiring is causing this issue.