Fault code P0252 – a step-by-step guide to diagnosing and fixing it

Error code P0252 is displayed and the check engine light is on - what does this mean?

The DTC P0252 is recognized by the OBD system when there is a problem with the injection pump control valve circuit "A" in diesel engines. This error code relates to the fuel injection system and can have slightly different interpretations for different manufacturers, but basically refers to the electrical control of the injection pump.

What causes can this error code have?

• Defective injection pump control valve
• Damaged wiring to the control valve
• Corroded or loose plug connections
• Defective engine control unit (ECU)
• Short circuit in the control valve circuit
• Mechanical defect on the injection pump
• Clogged fuel filter
• Low fuel pressure values

What symptoms occur in parallel with fault code P0252?

• Starting problems: The vehicle is difficult or impossible to start
• Loss of power: Significantly reduced engine power while driving
• Smooth engine running: Engine runs unevenly or jerks
• Increased fuel consumption: Noticeably higher diesel consumption
• Black smoke: Dark exhaust fumes from the exhaust pipe
• Emergency running program: Engine switches to safety mode

How can the problem with error code P0252 be rectified?

• The repair requires a systematic diagnosis, as several components may be affected.
• Replacement of the defective injection pump control valve with a new original part or high-quality spare part
• Repair or replacement of the damaged wiring between the control unit and control valve, including insulation
• Cleaning and renewal of all plug connections with contact spray and new seals
• Replacing the fuel filter and bleeding the entire fuel system
• Checking and, if necessary, replacing the engine control unit in the event of electronic defects
• Professional cleaning or repair of the injection pump in a specialist workshop
• Complete system diagnostics with professional OBD scanner to identify further error codes