P0644 Driver display communication (serial) - circuit malfunction

P0644 – OBD-II Trouble Code Technical Description

Trouble code P0644 indicates a communication error between multiple vehicle control modules.

What does the fault code mean P0644?

Trouble code P0644 indicates a failure in communication between the vehicle's various control modules. This code indicates a problem with the communication between the engine control module (PCM) and other vehicle ancillary modules, such as the anti-lock brake control module, alternative fuel control module, transmission control module, and others.

Possible reasons

Some of the possible causes of the P0644 trouble code are:

• Faulty wiring or connections: Poor contacts or breaks in the electrical wiring between the various control modules can cause communication failures.
• Control Module Malfunction: If one of the vehicle's control modules (such as the PCM or other auxiliary modules) experiences a malfunction, communication between the modules may be disrupted.
• Software Problems: Problems with the PCM or other control module software can cause errors in data transmission.
• Electrical Interference: Damage to electrical components or exposure to external electromagnetic fields can cause errors in data transmission.
• Other internal faults: There may be other internal faults in the control modules that can cause communication failures.

To accurately determine the cause, it is necessary to conduct a detailed diagnosis of the car.

What are the symptoms of a fault code? P0644?

Symptoms for DTC P0644 may vary depending on the specific vehicle and its control system, but some common symptoms may include:

• Check Engine Light: The appearance and/or flashing of the Check Engine light on your dashboard may be one of the first signs of a problem.
• Reduced performance: There may be a reduction in the performance of the engine or other systems controlled by modules that have communication problems.
• Unusual system behavior: Various vehicle systems, such as fuel, ignition, braking and others, may exhibit unusual behavior due to disturbances in communication.
• Misfires during engine operation: The engine may misfire or become unstable, especially at low or high speeds.
• Transmission problems: If communication problems affect the transmission control modules, it may cause the transmission to operate abnormally.
• Poor fuel consumption: In some cases, poor fuel consumption may be due to errors in the control systems caused by the P0644 code.

If you suspect this problem, it is recommended that you contact a qualified automotive technician for diagnosis and repair.

How to diagnose trouble code P0644?

Diagnosing the P0644 trouble code requires a systematic approach and may include the following steps:

• Checking code errors: You must first use a diagnostic scan tool to read the trouble codes, including the P0644 code. This will help determine which systems and components may be affected.
• Visual inspection of wiring: Check the wiring and connectors associated with the control modules, especially those that may be affected by a communication problem. Look for signs of damage, corrosion, or broken wiring.
• Checking the voltage level: Using a multimeter, check the voltage level in the circuit related to the sensors reference voltage. Compare the measured voltage with the manufacturer's recommended values.
• Testing control modules: Diagnose communication related control modules such as PCM, ECM and others. Make sure they function correctly and interact with each other.
• Checking sensors and position sensors: Check the operation of sensors associated with error-prone systems, including accelerator pedal position sensors, fuel pump sensors and others that may be associated with communication.
• Electrical Connection Testing: Check the electrical connections and grounding of the control modules to ensure they are secure and free from corrosion or oxidation.
• Updating the softwareNote: In some cases, updating the control module software may help resolve communication problems.
• Professional diagnostics: If you are unsure of your skills or do not have the necessary equipment, it is recommended that you contact a qualified automotive technician for additional diagnostics and repairs.

After diagnosing and eliminating the identified problems, it is necessary to clear the fault codes and conduct a test drive.

Diagnostic errors

When diagnosing DTC P0644, the following errors may occur:

• Skipping Wiring Check: Incorrect or incomplete wiring inspection may result in missed detection of damage, corrosion, or breaks that may be causing the problem.
• Faulty interpretation of scanner data: Incorrect interpretation of data obtained from the diagnostic scanner may lead to incorrect analysis of the cause of the problem.
• Incorrect component replacement: Replacing components without properly diagnosing and confirming that they are faulty may result in unnecessary costs and may not solve the problem.
• Misdiagnosis of other systems: Sometimes a problem with communication between control modules can be caused by a problem in another system in the vehicle. Incorrectly identifying and correcting such problems may cause P0644 to continue.
• Failed replacement of control modulesNote: Replacing control modules without correcting the actual cause of the problem may be ineffective and may not solve the communication problem.
• Software problems: Incorrect or incompatible software on the control modules can cause communication problems that may be incorrectly identified as P0644.

To avoid these errors, it is important to conduct diagnostics carefully, following the manufacturer's recommendations, use the correct equipment and testing procedures, and contact a qualified technician for additional assistance if necessary.

How serious is the fault code? P0644?

Trouble code P0644, which indicates problems with communication between various control modules in the vehicle, can be serious, especially if it causes problems with the functioning of vehicle systems. The inability of control modules to communicate can cause various systems to malfunction, which could affect vehicle safety, performance, and efficiency.

For example, if the engine control module cannot communicate with the brake control module, this may result in poor braking performance or even a dangerous driving situation. Also, problems with data exchange can lead to problems in systems that control emissions, which can lead to negative impacts on the environment.

Therefore, code P0644 should be considered serious and requires immediate attention. Not only does it indicate a problem in the vehicle's electronic system, but it can also have an impact on its safety and reliability.

What repair will help eliminate the code? P0644?

Troubleshooting trouble code P0644 may require several steps depending on the specific cause of the problem, several possible actions:

1. Checking electrical connections: The first step may be to check all electrical connections associated with the control modules, including connectors and wires. Any damaged or oxidized contacts should be replaced or repaired.
2. Diagnostics of control modules: Faulty control modules can lead to communication errors. Check each control module for faults and the need to replace them.
3. Software updateNote: In some cases, updating the control module software may resolve the communication problem. The update may be available from your authorized dealer or vehicle manufacturer.
4. Check the CAN network: If the error code indicates problems with the Controller Area Network (CAN), a thorough diagnosis of the network should be performed, including checking cables, connectors and other components.
5. Replacing modules: If after diagnostics it is revealed that one or more control modules are truly faulty and cannot be restored, then they should be replaced with new or serviceable ones.
6. Professional diagnostics: If you are unsure of your skills or access to the necessary equipment, it is recommended that you contact a qualified auto mechanic or service center for a more detailed diagnosis and troubleshooting of the problem.

It is important to note that repairing a P0644 code can be complex and require professional skills and equipment, so when in doubt, it is best to leave it to a professional.

How to Diagnose and Fix P0644 Engine Code - OBD II Trouble Code Explain

P0644 – Brand-specific information

Trouble code P0644, associated with the driver display and electrical communication circuit (serial) malfunction, can have different meanings depending on the specific vehicle brand. Here are some possible decodings for different brands:

• Ford: Driver display communication error.
• Chevrolet / GMC: Driver display, serial communication - circuit fault.
• Dodge / Ram: There is a problem with driver display communication.
• Toyota: Malfunction of the electrical communication circuit with the driver display.
• Honda: Driver display, serial communication - circuit fault.

These are just some of the possible decodings for specific car brands. For more accurate problem identification information, it is recommended that you consult the repair and service manual for your specific make and model of vehicle.