Fault code P0256 – a step-by-step guide to diagnosing and fixing it

The meaning of error code P0256 – Injection Pump Fuel Metering Control "B" Malfunction (Cam/Rotor/Injector)

P0256: Causes, signs and repairs

Error code P0256 is displayed and the check engine light is on - what does this mean?

The OBD system has detected a fault in the injection pump, more specifically a problem with the injection pump control valve A. This DTC P0256 mainly affects diesel vehicles and indicates that the electronic control of the fuel injection is faulty. For various manufacturers, this error code can also be referred to as "Injection Pump Fuel Metering Control A Range/Performance".

What can cause this error code?

Defective injection pump control valve
Damaged wiring to the control valve
Corroded or loose plug connections
Defective injection pump
Clogged fuel filter
Faulty engine control unit (ECU)
Low fuel pressure
Contaminated fuel
Defective fuel pressure sensor

What symptoms occur in parallel with fault code P0256?

Loss of power: The engine noticeably loses power, especially when accelerating or under load.
Unsteady idling: The vehicle runs unevenly or jerks when idling.
Starting problems: Difficulty starting the engine, especially in cold temperatures.
Increased fuel consumption: Noticeably higher diesel consumption than usual.
Black smoke: Dark exhaust fumes from the exhaust, especially when accelerating.

How can the problem of error code P0256 be rectified?

The repair requires a systematic diagnosis, as several components may be affected.
Replace the fuel filter: Replace the fuel filter and bleed the fuel system completely to remove blockages.
Replace injection pump control valve: Remove the defective control valve and install a new genuine replacement part with correct coding.
Check wiring and connectors: Check all electrical connections to the control valve for damage and clean or replace corroded connectors.
Clean the fuel system: Carry out a professional fuel system cleaning and use high-quality diesel fuel with additives.
Overhaul the injection pump: Have the injection pump overhauled at a specialist workshop or replace it with a reconditioned pump.
Reprogram the engine control unit: Carry out an ECU adjustment and install the latest software updates for the engine control unit.

FAQ - Frequently asked questions about DTC P0256

Can I continue driving with error code P0256?

Short journeys are possible, but you should have the vehicle repaired as soon as possible. Error code P0256 can lead to engine damage if it is ignored. Drive carefully and avoid heavy loads.

How much does it cost to repair error code P0256?

The costs vary depending on the cause: fuel filter (50-100€), control valve (200-500€), wiring repair (100-300€) or injection pump (1500-3000€). A precise diagnosis is therefore important.

How can I delete the error code P0256 myself?

You can clear the code with an OBD scanner, but it will return if the problem is not fixed. First have the cause repaired before permanently deleting the trouble code.

Is trouble code P0256 manufacturer-specific?

No, P0256 is a standardized EOBD code that can occur in all diesel vehicles. However, the exact designation may vary slightly between manufacturers.

Can bad fuel cause fault code P0256?

Yes, dirty or poor quality diesel can damage the injection pump control valve and trigger DTC P0256. Always use high-quality fuel and change the filter regularly.

How long does it take to repair error code P0256?

Between 2-8 hours, depending on the cause: Filter change (1-2h), control valve (3-5h), injection pump (6-8h). The diagnosis also takes about 1 hour.

Vehicles in which fault code P0256 occurs most frequently

Fault code P0256 is a specific diesel engine fault code that indicates problems with the injection pump control valve and mainly occurs in older diesel vehicles with mechanical or electromechanical injection pumps, but is most common in the following vehicles:

BMW: 320d, 330d, 520d, 530d, X3, X5 (2000-2010)
Mercedes-Benz: C220 CDI, E220 CDI, E320 CDI, ML320 CDI, Sprinter (1999-2009)
Audi: A4 TDI, A6 TDI, A8 TDI, Q7 TDI (2000-2008)
Volkswagen: Passat TDI, Touareg TDI, Crafter, LT (2000-2010)
Ford: Transit, Focus TDCi, Mondeo TDCi (2001-2011)
Opel: Vectra CDTI, Insignia CDTI, Vivaro (2002-2012)
Peugeot: 307 HDI, 407 HDI, 607 HDI, Boxer (2001-2010)
Renault: Laguna dCi, Espace dCi, Master dCi (2001-2011)

If the code P0256 occurs in your vehicle, you should first check the fuel filter and check the fuel system for contamination. As this error code is often associated with costly repairs to the injection pump, we recommend a professional diagnosis at a specialist workshop to avoid unnecessary repair costs. Regular maintenance and the use of high-quality diesel fuel can significantly reduce the occurrence of this trouble code.

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