Fault code P1639 – a step-by-step guide to diagnosing and fixing it

Error code P1639 is displayed and the check engine light is on - what does this mean?

The DTC P1639 is a manufacturer-specific fault code that is recognized by the OBD system and typically indicates problems with the engine control unit or electronic components. This code can have different meanings for different vehicle manufacturers, but usually refers to communication errors between control units or sensor problems.

What causes can this error code have?

• Defective cable connections between control units
• Damaged or corroded plug connections
• Faulty engine control unit (ECU)
• Defective CAN bus or other communication lines
• Voltage problems in the vehicle electrics
• Defective sensors in the engine management system
• Software errors in the engine control unit
• Damaged ground or power supply lines

What symptoms occur in parallel with fault code P1639?

• Starting problems: The vehicle is difficult or impossible to start
• Uneven idling: The engine runs unevenly when stationary
• Loss of power: Reduced engine power while driving
• Jerking: The vehicle jerks when accelerating
• Increased fuel consumption: Significantly higher consumption than normal
• Emergency running program: The vehicle switches to emergency running mode

How can the problem with error code P1639 be rectified?

• The repair requires a systematic diagnosis, as this is a manufacturer-specific code.
• Carry out a complete OBD diagnosis and read out all stored fault codes, then determine the specific meaning of the P1639 code for the respective vehicle model
• Check all electrical connections and plug connections in the engine compartment for corrosion, damage or loose contacts and clean or replace if necessary
• Test the CAN bus system and communication lines between the control units using a multimeter or oscilloscope and repair defective lines
• Check the engine control unit (ECU) for functionality and replace or repair the control unit in the event of a hardware defect
• Carry out a software update for the engine control unit, if available from the manufacturer, to fix known bugs
• Check the power supply and ground connections of the entire engine system and repair faulty connections