Fault code P1641 – a step-by-step guide to diagnosing and fixing it

Error code P1641 is displayed and the check engine light is on - what does this mean?

The DTC P1641 is recognized by the OBD system when a problem with the fuel pump relay circuit is detected. This manufacturer-specific fault code mainly affects the fuel system and the electrical control of the fuel pump. The exact definition may vary slightly for different vehicle manufacturers, but generally refers to faults in the fuel pump control system.

What causes can this error code have?

• Defective fuel pump relay
• Damaged wiring to the fuel pump
• Loose or corroded plug connections
• Defective fuel pump
• Faulty fuse in the fuel pump circuit
• Defective engine control unit (ECM/PCM)
• Broken ground wire
• Overloading of the electrical system

What symptoms occur in parallel with fault code P1641?

• Starting problems: The vehicle is difficult or impossible to start
• Engine misfires: Irregular engine running, especially at low engine speeds
• Loss of power: Reduced engine power while driving
• Jerking: The vehicle jerks or stutters when accelerating
• Engine stalling: Engine stalls while driving
• Smell of fuel: Smell of gasoline in or around the vehicle

How can the problem of error code P1641 be rectified?

• The repair requires a systematic diagnosis of the fuel pump circuit and its components.
• Replace the fuel pump relay and check all relay plug connections for tightness and corrosion
• Check the fuel pump fuse and replace if necessary, also checking the fuse holder for damage
• Test the wiring between the fuel pump and control unit for continuity and short circuits using a multimeter
• Check the fuel pump electrically and have it completely replaced if defective
• Clean all plug connections in the fuel system, treat with contact spray and connect firmly
• Test the engine control unit for functionality and have it reprogrammed or replaced if necessary