P0558 High Brake Booster Pressure Sensor Circuit

What Does It Mean?

This is a generic powertrain diagnostic trouble code (DTC) that applies to OBD-II vehicles equipped with a brake booster pressure sensor. This may include, but is not limited to, vehicles from Fiat, Alfa Romeo, Nissan, Ford, Dodge, Pontiac, Chevrolet, Acura, Subaru, Hyundai, etc. While generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

Fault code P0558 is one of several possible codes associated with the brake booster pressure sensor circuit.

This code indicates that the Powertrain Control Module (PCM) has detected a malfunction affecting the operation of the brake booster pressure sensor circuit. Common codes related to brake booster pressure sensor circuit malfunctions include P0555, P0556, P0557, P0558, and P0559. The specific situation determines which code is triggered by the PCM, and the brake warning light may illuminate or flash during braking.

The purpose of the brake booster pressure sensor circuit is to monitor the amount of pressure (vacuum) applied to the brake booster. The circuit is controlled by the PCM to adapt to various braking conditions and adjust pressure to assist with brake pedal operation. This process is essential for power brakes to function correctly, allowing the vehicle to slow down or stop safely with minimal foot pressure applied to the brake pedal.

Code P0558 is set by the PCM when the brake booster pressure sensor circuit reads a voltage higher than expected.
How Severe Is This DTC?

The severity of this code varies depending on the specific malfunction and will escalate if not addressed promptly. At some point, vehicle safety may become compromised, requiring immediate attention.

Photo of a Brake Booster Pressure (Vacuum) Sensor:

What Are Some Symptoms of the Code?

Symptoms of a P0558 fault code may include:

Brake warning light flashing during braking
Brake warning light staying on
Service engine soon light illuminated
Increased effort required to press the brake pedal

What Are Some Common Causes of the Code?

Causes

of this P0558 code may include:

Faulty brake booster pressure sensor
Worn or damaged vacuum lines
Corroded or damaged connector
Damaged or faulty wiring
Defective brake booster
Faulty PCM

What Are the P0558 Troubleshooting Steps?

The first step in troubleshooting any malfunction is to check technical service bulletins for known issues with the specific vehicle.

Locate all components associated with the brake booster pressure sensor circuit. This includes the brake booster pressure sensor, brake booster, vacuum lines, wiring, connectors, and the PCM in a simplex system. Once these components are located, perform a thorough visual inspection to check for obvious defects such as scraping, rubbing, exposed wires, or burn marks. Connectors should also be inspected for corrosion buildup or damaged pins. Vacuum lines should be checked for security, weather cracking, leaks, and overall service condition.
Advanced Steps

Advanced steps are highly vehicle-specific and require appropriate advanced equipment to perform accurately. These procedures necessitate a digital multimeter and vehicle-specific technical references. Voltage requirements will vary significantly based on the specific year, make, and model of the vehicle.
Circuit Checks

Voltage requirements depend on the specific vehicle, brake booster pressure sensor circuit configuration, and integrated components. Technical data must be referenced to determine the correct voltage range for the brake booster pressure sensor and the appropriate troubleshooting sequence. Correct input voltage to a sensor with no output voltage typically indicates an internal failure.

If this process identifies a missing power source or ground, continuity tests may be required to verify the condition of wiring and connectors. Continuity tests should always be performed with the circuit power disconnected, and normal readings should show 0 ohms of resistance unless otherwise specified by technical data. Resistance or lack of continuity indicates faulty wiring or connectors that are shorted or open and need repair or replacement.
Common Repairs

Replacing a faulty brake booster pressure sensor
Cleaning corrosion from connectors
Repairing or replacing wiring
Replacing the brake booster
Flashing or replacing the PCM

I hope the information in this article has been helpful in guiding you in the right direction to resolve the issue with your brake booster pressure sensor fault code. This article is strictly informational, and specific technical data and service bulletins for your vehicle should always take precedence.

P0559 Intermittent Brake Booster Pressure Sensor Circuit

What Does It Mean?

This is a generic powertrain diagnostic trouble code (DTC) and applies to OBD-II vehicles equipped with a brake booster pressure sensor. This may include, but is not limited to, vehicles from Fiat, Alfa Romeo, Nissan, Ford, Dodge, Pontiac, Chevrolet, Acura, Subaru, Hyundai, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

Fault code P0559 is one of several possible codes associated with the brake booster pressure sensor circuit.

Code P0559 is set by the PCM when the brake booster pressure sensor circuit experiences an intermittent output voltage signal issue.
How Severe Is This DTC?

The severity of this code varies depending on the specific malfunction and will escalate if not addressed promptly. At some point, vehicle safety could become compromised, requiring immediate attention.

Photo of a Brake Booster Pressure (Vacuum) Sensor:

What Are Some Symptoms of the Code?

Symptoms of a P0559 fault code may include:

Brake warning light flashing during braking
Brake warning light staying on
Illuminated service engine soon light
Increased effort required to press the brake pedal

What Are Some Common Causes of the Code?

Causes

of this P0559 code may include:

Faulty brake booster pressure sensor
Worn or damaged vacuum lines
Corroded or damaged connector
Damaged or faulty wiring
Defective brake booster
Faulty PCM

What Are the P0559 Troubleshooting Steps?

The first step in the troubleshooting process for any malfunction is to check technical service bulletins for known issues with the specific vehicle.

Locate all components associated with the brake booster pressure sensor circuit. This includes the brake booster pressure sensor, brake booster, vacuum lines, wiring, connectors, and the PCM in a simplex system. Once these components are located, perform a thorough visual inspection to check for any obvious defects such as chafing, rubbing, exposed wires, or burn marks. Connectors should also be inspected for corrosion buildup or damaged pins. Vacuum lines should be checked for security, weather cracking, leaks, and overall condition.
Advanced Steps

If this process identifies a missing power source or ground, continuity tests may be necessary to verify the condition of wiring and connectors. Continuity tests should always be performed with the circuit power off, and normal readings should show 0 ohms resistance unless otherwise specified by technical data. Resistance or lack of continuity indicates faulty wiring or connectors that are shorted or open and need repair or replacement.
Common Repairs

Replacing a faulty brake booster pressure sensor
Cleaning corrosion from connectors
Repairing or replacing wiring
Replacing the brake booster
Flashing or replacing the PCM

P055A, P055B, P055C, P055D, P055E, P055F ISO/SAE Reserved

P016A, P016B, P016C, P016D, P016E, P016F ISO/SAE Reserved

P0560 System Voltage Malfunction

📌 Error Code P0560: Causes, Symptoms, and Solutions

🔍 What Does Code P0560 Mean?

Code P0560 is a generic diagnostic code from the Powertrain group. It generally applies to all vehicles since 1996, including Hyundai, Toyota, Saab, Kia, Honda, Dodge, Ford, and Jaguar.

This code is related to the vehicle’s charging system and is triggered when the Powertrain Control Module (PCM) detects an anomaly in the electrical voltage.

The PCM monitors the charging system voltage by checking the ignition power circuit. If the voltage is too high or too low, an error code is recorded. This issue is strictly electrical and can be caused by various factors.

⚠️ Symptoms of Code P0560

A P0560 code can cause the following symptoms:
✅ Malfunction Indicator Light (Check Engine) illuminated
✅ Red battery light activated
✅ Transmission not shifting properly
✅ Engine not starting or stalling after starting
✅ Decreased fuel economy

🔧 Possible Causes

The most common causes of this code are:

Cable between the alternator and battery with high resistance (poor connection)
Open circuit or high resistance between the alternator and PCM
Faulty alternator (most common cause)
Failing PCM (rare)

🛠️ Diagnostic and Repair Procedures

✅ 1. Check Technical Service Bulletins (TSBs)

First, consult TSBs specific to your vehicle. Some manufacturers recognize this issue and offer official solutions, which can save you time and money.

✅ 2. Test the Charging System Voltage

Start the vehicle
Activate electrical consumers (headlights, ventilation, etc.)
Use a digital voltmeter (DVOM) to measure battery voltage
- Normal value: between 13.2V and 14.7V
- If <12V or >15.5V, the problem is likely with the alternator

If in doubt, you can have the battery and alternator tested for free at a workshop or auto parts store.

✅ 3. Check Electrical Connections

Inspect cables and connectors of the PCM and alternator.
Check for exposed, burnt, or corroded wires.
Clean connector terminals with electrical contact cleaner.

✅ 4. Clear the Code and Test Again

Delete error codes with a diagnostic tool.
If the code does not return, the problem was likely intermittent.
If the code returns, proceed to the next step.

✅ 5. Check PCM Power and Ground

Disconnect the negative battery cable.
Disconnect the PCM harness.
Reconnect the battery and turn on the ignition.
Use a voltmeter to test PCM power and ground:
- If the voltage is lower than battery voltage, the problem is with the wiring.
- Check the ground using a test light.

✅ 6. Final Check: The PCM

If all previous steps are correct but the P0560 code persists, the issue may be with the PCM itself.
⚠️ Warning: Replacing the PCM requires vehicle-specific programming and should be done by a professional.

📌 Conclusion

Code P0560 is usually caused by a faulty alternator or an electrical connection problem. A simple check of the charging system and cleaning the connectors can often resolve the issue. If the problem persists after these checks, advanced PCM diagnostics are necessary.

Need help? Consult an auto repair shop or use an OBD-II diagnostic tool to confirm the exact cause. 🚗💡

P0561 Unstable System Voltage

What does it mean?

This generic powertrain/engine diagnostic code generally applies to all 1996 vehicles, including but not limited to Kia, Hyundai, Jeep, Mercedes, Dodge, Ford, and GM vehicles.

The PCM controls the charging system to some extent on these vehicles. The PCM can control the charging system by controlling a power supply or ground circuit to the voltage regulator inside the alternator.

The Powertrain Control Module (PCM) monitors the ignition power supply circuit to determine if the charging system is operating. If the voltage is too high or too low, a trouble code will be set. If voltage is not present when it should be, a trouble code will be set. This is strictly an electrical issue.

Troubleshooting steps may vary depending on the manufacturer, the type of charging system control, and the wire colors.

Symptoms

Symptoms of a P0561 engine code may include:

Malfunction Indicator Light illuminated
Red battery light illuminated
Transmission may not shift
Engine may not start or if it starts, it may stall and die
Reduced fuel economy

Causes

Possible causes for this code being set are:

High resistance in the cable between the alternator and the battery – possible
High resistance / open circuit between the alternator and the control module – possible
Faulty alternator – most common
Failed PCM – unlikely

Diagnostic and Repair Procedures

A good starting point is always to check the Technical Service Bulletins (TSBs) for your particular vehicle. Your issue may be a known problem with a known fix issued by the manufacturer and can save you time and money when diagnosing.

The most common cause of this code is low battery voltage / a disconnected battery / a malfunctioning charging system (faulty alternator). While we’re on the subject, let’s not forget to check the most overlooked part of the charging system, the alternator belt!

First, check the charging system. Start the vehicle. Turn on the headlights and the blower fan on high speed to load the electrical system. Using a Digital Volt Ohm Meter (DVOM), check the battery voltage. It should be between 13.2 volts and 14.7 volts. If the voltage is well below 12 volts or above 15.5 volts, diagnose the charging system, focusing primarily on the alternator. If in doubt, have the battery, starting, and charging system tested at a local parts store/auto repair shop. Most will perform this service for a small fee, if not for free, and will usually give you a printout of the test results.

If the voltage was correct and you have a scan tool, clear the diagnostic codes from the memory and see if this code returns. If it does not, it is more than likely that this code is intermittent or is a history/memory code and no further diagnosis is required.

If the P0561 code returns, locate the PCM on your specific vehicle. Once located, visually inspect the connectors and wiring. Look for chafing, rubbing, bare wires, burns, or melted plastic. Disconnect the connectors and carefully inspect the terminals (the metal parts) inside the connectors. See if they look burned or have a greenish tint indicating corrosion. Use electrical contact cleaner and a plastic bristle brush if cleaning the terminals is necessary. Let it dry and apply electrical grease where the terminals make contact.

Next, clear the diagnostic codes from the memory with the scan tool and see if this code returns. If it does not, the connections were likely your problem.

If the P0561 code returns, we will need to check the voltages at the PCM. First, disconnect the negative battery cable at the battery. Then, disconnect the wiring harness going to the PCM. Reconnect the battery cable. Turn the ignition on. With a DVOM, test the PCM ignition power supply circuit (red lead to the PCM ignition power supply circuit, black lead to a good ground). If there is less than battery voltage on this circuit, repair the wiring between the PCM and the ignition switch.

If that checks out, verify that you have a good ground at the PCM. Connect a test light to the positive 12V battery (red terminal) and touch the other end of the test light to the ground circuit going to the PCM ignition power supply circuit ground. If the test light does not illuminate, that would indicate the circuit problem. If it lights up, wiggle the wiring harness going to the PCM to see if the test light flickers, indicating an intermittent connection.

If all previous tests have passed and you continue to get a P0561, this would most likely indicate a faulty PCM. If in doubt, seek assistance from a qualified automotive diagnostician. PCMs need to be programmed or calibrated to the vehicle in order to be installed correctly.

P0562 Low System Voltage

What does it mean?

This generic powertrain/engine diagnostic code generally applies to all 1996 vehicles, including but not limited to Kia, Hyundai, Jeep, Mercedes, Dodge, Ford, and GM vehicles.

The Powertrain Control Module (PCM) monitors the ignition power supply circuit to determine if the charging system is operating. If the voltage is too low, a fault code will be set. This is strictly an electrical issue.

Troubleshooting steps may vary depending on the manufacturer, the type of charging system control, and the wire colors.

Symptoms

Symptoms of a P0562 engine code may include:

Malfunction indicator light illuminated
Red battery light illuminated
Transmission may not shift
Engine may not start or if it starts, it may stall and die
Reduced fuel economy

Causes

Possible causes for this code being set are:

High resistance in the cable between the alternator and the battery – possible
High resistance/open circuit between the alternator and the control module – possible
Faulty alternator – most common
Failed PCM – unlikely

Diagnostic and Repair Procedures

A good starting point is always to check the Technical Service Bulletins (TSBs) for your specific vehicle. Your problem may be a known issue with a known fix released by the manufacturer and can save you time and money when diagnosing.

The most common cause of this code is low battery voltage/a battery that has been disconnected/a malfunctioning charging system (faulty alternator). While we’re on the subject, let’s not forget to check the most overlooked part of the charging system, the alternator belt!

First, check the charging system. Start the vehicle. Turn on the headlights and the heater fan on high speed to load the electrical system. Using a digital voltmeter (DVOM), check the battery voltage. It should be between 13.2 volts and 14.7 volts. If the voltage is well below 12 volts or above 15.5 volts, diagnose the charging system, focusing primarily on the alternator. If in doubt, have the battery, starting, and charging system tested at a local auto parts store/auto repair shop. Most will perform this service for a small fee, if not for free, and will usually give you a printout of the test results.

If the P0562 code returns, locate the PCM on your specific vehicle. Once located, visually inspect the connectors and wiring. Look for scratches, rubbing, bare wires, burns, or melted plastic. Disconnect the connectors and carefully inspect the terminals (the metal parts) inside the connectors. See if they look burnt or have a greenish tint indicating corrosion. Use electrical contact cleaner and a plastic bristle brush if cleaning the terminals is necessary. Let it dry and apply electrical grease where the terminals make contact.

Next, clear the diagnostic codes from the memory with the scan tool and see if this code returns. If it does not, the connections were probably your problem.

If the P0562 code returns, we will need to check the voltages at the PCM. First, disconnect the negative battery cable at the battery. Then, disconnect the wiring harness going to the PCM. Reconnect the battery cable. Turn the ignition on. With a DVOM, test the PCM ignition power supply circuit (red wire to the PCM ignition power supply circuit, black wire to a good ground). If there is less than battery voltage on this circuit, repair the wiring between the PCM and the ignition switch.

If that checks out, verify that you have a good ground at the PCM. Connect a test light to the positive 12V battery (red terminal) and touch the other end of the test light to the ground circuit going to the ground of the PCM ignition power supply circuit. If the test light does not illuminate, that would indicate a problem with the circuit. If it lights up, wiggle the wiring harness going to the PCM to see if the test light flickers, indicating an intermittent connection.

If all previous tests have passed and you continue to get a P0562, this would most likely indicate a faulty PCM. If in doubt, seek assistance from a qualified automotive diagnostician. PCMs need to be programmed or calibrated to the vehicle in order to be installed correctly.

P0563 High System Voltage

What does it mean?

This generic powertrain/engine diagnostic code generally applies to all 1996 vehicles, including but not limited to Kia, Hyundai, Jeep, Mercedes, Dodge, Ford, and GM vehicles.

The Powertrain Control Module (PCM) monitors the ignition power supply circuit to determine if the charging system is operating. If the voltage is too high, a trouble code will be set. This is strictly an electrical issue.

Troubleshooting steps may vary depending on the manufacturer, the type of charging system control, and the wire colors.

Symptoms

Symptoms of a P0563 engine code may include:

Malfunction indicator light illuminated
Red battery light illuminated
Transmission may not shift
Engine may not start or if it starts, it may stall and die
Reduced fuel economy

Causes

Possible causes for this code being set are:

High resistance in the cable between the alternator and the battery – possible
Low resistance / open circuit between the alternator and the control module – possible
Faulty alternator – most common
Failed PCM – unlikely

Diagnostic and Repair Procedures

A good starting point is always to check the Technical Service Bulletins (TSBs) for your specific vehicle. Your issue may be a known problem with a known fix issued by the manufacturer and can save you time and money when diagnosing.

First, check the charging system. Start the vehicle. Turn on the headlights and the blower fan on high speed to load the electrical system. Using a digital voltmeter (DVOM), check the battery voltage. It should be between 13.2 volts and 14.7 volts. If the voltage is above 15.5 volts, diagnose the charging system, focusing primarily on the alternator. If in doubt, have the battery, starting, and charging system tested at a local parts store/auto repair shop. Most will perform this service for a small fee, if not for free, and will usually provide you with a printout of the test results.

If the P0563 code returns, locate the PCM in your specific vehicle. Once located, visually inspect the connectors and wiring. Look for scratches, rubbing, bare wires, burns, or melted plastic. Separate the connectors and carefully inspect the terminals (the metal parts) inside the connectors. See if they look burnt or have a greenish tint indicating corrosion. Use electrical contact cleaner and a plastic-bristled brush if cleaning the terminals is necessary. Let it dry and apply electrical grease where the terminals make contact.

Next, clear the diagnostic codes from the memory with the scan tool and see if this code returns. If it does not, the connections were likely your problem.

If the P0563 code returns, we will need to check the voltages at the PCM. First, disconnect the negative battery cable at the battery. Then, disconnect the wiring harness going to the PCM. Reconnect the battery cable. Turn the ignition on. With a DVOM, test the PCM ignition power supply circuit (red lead to the PCM ignition power supply circuit, black lead to a good ground). If there is less than battery voltage on this circuit, repair the wiring between the PCM and the ignition switch.

If that is okay, check that you have a good ground at the PCM. Connect a test light to the positive 12V battery (red terminal) and touch the other end of the test light to the ground circuit going to the PCM ignition power supply circuit ground. If the test light does not illuminate, this would indicate a circuit problem. If it illuminates, wiggle the wiring harness going to the PCM to see if the test light flickers, indicating an intermittent connection.

If all previous tests have passed and you continue to get a P0563, this would most likely indicate a faulty PCM. If in doubt, seek assistance from a qualified automotive diagnostician. PCMs need to be programmed or calibrated to the vehicle in order to be installed correctly.

P0564 Cruise Control Multifunction Input A Circuit

What Does It Mean?

This is a generic powertrain diagnostic trouble code (DTC) and generally applies to OBD-II vehicles. This may include, but is not limited to, vehicles from Mazda, Alfa Romeo, Ford, Land Rover, Jeep, Dodge, Chrysler, Chevy, Nissan, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

Cruise control was developed for our comfort. Its sole purpose is to manually maintain the vehicle speed set by the operator (via steering wheel buttons, the multifunction switch (i.e., turn signals, cruise control, wipers, etc.) mounted on the steering column, etc.)

Meanwhile, the operator no longer needs to control the accelerator pedal, and if the vehicle is equipped with an automatic transmission (A/T), it can also control and adjust shift points based on real-time driving condition requirements.

Generally speaking here, this code would lead me to believe we are talking about the multifunction switch on your steering column. That said, location possibilities vary significantly from one manufacturer to another, so research accordingly. The cruise control button would be a good place to start narrowing down locations. This code refers to a specific input circuit in the cruise control system. To determine which wire/circuit to focus on, refer to the service manual; the letters in the codes can and will be your best reference regarding identifying the wire/circuit you are trying to diagnose/test.

In case of a fault in the cruise control multifunction “A” input circuit, the Engine Control Module (ECM) proactively illuminates the instrument cluster with P0564 and related codes (P0564, P0578, P0579, P0580, and P0581).

Regarding the letter “A,” it could be to distinguish a connector, wire, circuit group, etc. That said, manufacturer specifications are the best resource you can have for this.

The P0589 code will be triggered by the ECM when a general fault is detected by the ECM in the cruise control multifunction switch “A” input circuit(s).

A Cruise Control Stalk:

How Severe Is This DTC?

Low severity for almost all cruise control faults, that said, there are many exceptions. For the most part, however, this fault should not be a source of serious concern. That said, when it comes to electrical issues, they generally worsen over time. Most of the time, this fault will be moderately affordable to fix.

Obviously, this is very subjective, so be sure to shop around for the best prices and get multiple quotes/diagnostic strategies; who knows, work orders alone might help you determine what you’re dealing with. Always stay on top of general vehicle maintenance.
What Are Some of the Symptoms of the Code?

Symptoms of a P0564 Fault Code May Include:

Abnormal vehicle speeds with cruise control activated
Inoperative cruise control
Cruise control indicator light on regardless of switch position
Unable to set cruise control to desired speed

What Are Some Common Causes of the Code?

Causes

of This P0564 Code May Include:

Faulty multifunction/cruise control switch (i.e., stuck, broken, missing, etc.)
Wiring issue (e.g., rubbing on steering column/dashboard parts, water intrusion, corrosion, etc.)
Connector malfunction (e.g., corroded pins, broken plastic tabs, swollen connector body, etc.)
Liquids/dirt/grime in the cruise control button/switch causing abnormal mechanical operation
ECM problem (e.g., water intrusion into the computer body, internal short circuit, internal overheating, etc.)

What Are the Troubleshooting Steps for P0564?
Basic Step #1

Once your vehicle’s multifunction/cruise control switch is located, visually inspect it for any type of contamination. It is very easy for plastic buttons/switches to become dirty/greasy/sticky, making them faulty and/or operating abnormally. Ensure the mechanical operation of the switch is smooth and fluid. Any issues here should be addressed immediately. If your specific scan tool/OBD reader has the capabilities, feel free to observe the electronic operation of the switch via DATA STREAM (the mode name varies here between readers, but the important thing is to find a mode to observe real-time data).

TIP: Be careful not to spray cleaning solutions directly onto the button. Lightly dampen a clean cloth with water, soap and water, dashboard cleaner, etc., and carefully remove debris from the switch crevices. A compressed air gun will help remove debris without making the situation worse.
Basic Step #2

To access the connectors and harnesses involved in the cruise control/multifunction switch input circuit, you may need to remove some dashboard plastics/covers. Be gentle when working with plastic. Comfortable ambient temperatures always contribute to the ease of disassembling/assembling dashboard/interior plastics.

If you can easily access the connector, you may be able to apply specific troubleshooting steps provided by your service manual. Testing switches will most likely involve recording electrical values using your multimeter. This may include using the switch during recording and/or static tests. Refer to the specific make and model service manual for a “diagnostic flowchart.”
Basic Step #3

A problem within the ECM is, most of the time, the last resort in diagnosis. Since this might be one of the most expensive electronic repairs you could perform on your vehicle, leave this to the professionals.

P0565 Cruise Control Signal Malfunction

What Does It Mean?

This is a generic diagnostic trouble code (DTC) for the powertrain and generally applies to OBD-II equipped vehicles with cruise control. This may include, but is not limited to, vehicles from Peugeot, Ford, Nissan, Chevrolet, Hyundai, VW, Audi, Citroen, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

In the vehicle’s cruise control option, there are many functions. The operator can not only set a specific vehicle speed, which is then automatically maintained using many sensors, switches, modules, among many other components, but can also adjust the speed electronically (i.e., “set -” & “resume +”), temporarily change the speed while remembering the previous speed (e.g., for overtaking other vehicles, unexpected stopping/slowing down), among others.

Since most of the functions mentioned in the description of P0565 and related codes (P0566, P0567, P0568, P0569, P0570, etc.) are contained within a switch/component, it should be fairly straightforward to locate the input mechanisms (buttons, switches, controls, etc.) involved. That said, some common names for these components are: Multifunction Switch, Steering Wheel Controls, Cruise Control Switch, Cruise Control Module, Accessory Switch, etc.

What happened, in the case of this code, is that the ECM (Engine Control Module) detected a malfunction or malfunctions in the signal circuit. In other words, something went wrong in the circuit of the function mentioned in the description.

When the ECM detects a signal malfunction in one or more of the many cruise control functions, it illuminates the CEL (Check Engine Light) with P0565 and/or related codes. Most likely, the use of this function will be disabled and/or will behave abnormally.

The P0565 code is set when the ECM detects a signal malfunction in the “On/Off” circuit’s ON signal.

An Example of Cruise Control Buttons on a Steering Wheel:

How Severe Is This DTC?

The severity would be considered moderately low. Even if you lose all cruise control functionality, you can still operate the vehicle safely. Regarding potential additional damage if left unaddressed, this would be a rare case where you might be able to neglect it if, say, your vehicle is old and you can live without cruise control, or you cannot afford to repair the vehicle.

That being said, it is possible that neglecting ANY electrical issue for a long enough time could lead to further damage.

What Are Some of the Symptoms of the Code?

Symptoms of a P0565 trouble code may include:

The cruise control indicator light on the dashboard does not illuminate or is stuck on
Cruise control inoperative
Unable to set the cruise control to the desired speed or the speed is erratic
Certain functions within the cruise control system are non-operational (e.g., Resume, Set, +, -, Coast, Accelerate)
Controls do not work consistently

What Are Some of the Common Causes of the Code?

Causes of this P0565 code may include:

Faulty and/or damaged cruise control switch or buttons inside the switch
Connector(s) not making proper and effective electrical connection
Wire(s) in the cruise control harness have been chafed and/or damaged, causing a short circuit, open resistance, etc.
Cruise control switch assembly contaminated by liquid (coffee, soda, juice, etc.)
ECM problem
Faulty cruise control module
BCM (Body Control Module) problem
Overheated parts causing malfunction

What Are the Troubleshooting Steps for P0565?

Basic Step #1

The first thing I would do here is visually inspect the cruise control switch/module. Sometimes buttons are missing, soda has jammed a button in one position, buttons are loose and not making proper electrical connections. That said, ensure the buttons that control the cruise functions move freely and are not contaminated by potentially damaging particles and/or dirt. You will also want to note ALL malfunctions or anomalies with the cruise functions.

Basic Step #2

Does the cruise control indicator light illuminate in the instrument cluster when the cruise control is manually activated? If not, you may want to check if there is a fuse for the circuit. This information should be found in the make and model’s service manual. Replace any blown fuses with new, manufacturer-approved fuses.

Basic Step #3

To access the cruise control switch/module harness, generally, you will need to remove some dashboard components (e.g., steering column covers, airbag module in the steering wheel, etc.). To locate the specific wire involved in the fault, you will certainly need the appropriate wiring diagram for your vehicle. These vary significantly for many reasons. Always obtain the proper service information BEFORE performing anything too invasive.

Basic Step #4

It’s a good idea to ensure your ABS (Anti-lock Braking System) is in good working order and that no ABS warning light is illuminated on the dashboard. The ABS uses many sensors, including speed sensors which, if malfunctioning, could trick the computers into thinking the vehicle is traveling faster or slower than the actual speed.

P0566 Malfunction in the Cruise Control Shut-off Signal

What does it mean?

In the vehicle’s cruise control option, there are many functions. The operator can not only set a specific speed for the vehicle, which can be automatically maintained using many sensors, switches, modules, among many other components, but can also adjust the speed electronically (i.e., “set -” & “resume +”), temporarily change the speed while remembering the previous speed (e.g., overtaking vehicles, unexpected stopping/slowing), among others.

Since most of the functions mentioned in the description of P0566 and related codes (P0565, P0567, P0568, P0569, P0570, etc.) are contained within a switch/component, it should be fairly straightforward to locate the input mechanisms (buttons, switches, controls, etc.) involved. That said, some common names for these components include: Multifunction Switch, Steering Wheel Controls, Cruise Control Switch, Cruise Control Module, Accessory Switch, etc.

What happened, in the case of this code, is that the ECM (Engine Control Module) detected one or more malfunctions in the signal circuit. In other words, something went wrong in the circuit of the function mentioned in the description.

When the ECM detects a signal malfunction in one or more of the many cruise control functions, it illuminates the CEL (Check Engine Light) with P0566 and/or related codes. Most likely, the use of this function will be disabled and/or will behave abnormally.

The code P0566 is set when the ECM detects a signal malfunction in the OFF signal of the “On/Off” circuit.

An example of cruise control buttons on a steering wheel:

How severe is this DTC?

The severity would be considered moderately low. Even if you lose all cruise control functionality, you can still operate safely. Regarding additional damage if not monitored, this would be a rare case where you might be able to neglect it if, say, your vehicle is old and you can live without cruise control, or you cannot afford to repair the vehicle.

That said, it is possible that neglecting ANY electrical issue long enough could lead to additional damage.
What are some of the symptoms of the code?

Symptoms of a P0566 trouble code may include:

The cruise control indicator on the dashboard does not light up or is stuck
Inoperative cruise control
Unable to set the cruise control to the desired speed or the speed is erratic
Certain functions in the cruise control system are non-operational (e.g., resume, set, +, -, coast, accelerate)
Controls do not work consistently

What are some common causes of the code?

Causes

of this P0566 code may include:

Faulty and/or damaged cruise control switch or buttons inside the switch
Connector(s) not making a proper and effective electrical connection
Wire(s) in the cruise control harness have been stripped and/or damaged, causing a short circuit, open circuit, resistance, etc.
Cruise control switch assembly contaminated by liquid (coffee, soda, juice, etc.)
ECM problem
Faulty cruise control module
BCM (Body Control Module) problem
Overheated parts causing malfunction

What are the troubleshooting steps for P0566?
Basic Step #1

The first thing I would do here is visually inspect the cruise control switch/module. Sometimes buttons are missing, soda has jammed a button in one position, buttons are loose and not making proper electrical connections. That said, ensure that the buttons controlling the cruise functions move freely and are not contaminated by potentially damaging particles and/or dirt. You will also want to record ALL malfunctions or anomalies in the cruise functions.
Basic Step #2

Does the cruise control indicator light up in the instrument cluster when the cruise control is manually activated? If not, you may want to check if there is a fuse for the circuit. This information should be found in the brand and model’s service manual. Replace any blown fuses with new, manufacturer-approved fuses.
Basic Step #3

To access the cruise control switch/module harness, typically, you will need to remove some dashboard parts (e.g., steering column cover, airbag module in the steering wheel, etc.). To locate the specific wire involved in the fault, you will certainly need the appropriate wiring diagram for your vehicle. These vary significantly for many reasons. Always obtain the proper service information BEFORE performing anything too invasive.
Basic Step #4

It is a good idea to ensure that your ABS (anti-lock braking system) is in good working order and that no ABS light is illuminated on the dashboard. ABS uses many sensors, including speed sensors that, if malfunctioning, could trick the computers into thinking the vehicle is traveling faster or slower than the actual speed.