P0256: Injection Pump Fuel Metering Control B (Cam/Rotor/Injector)

What does P0256 mean?

These codes cover the electrically controlled fuel metering actuator on a diesel injection pump – on common rail usually an inlet metering valve on the high-pressure pump that sets how much fuel is compressed. Actuator B is a second metering actuator, for example on pumps with two metering valves such as on Saab's 3.0 V6 diesel. P0256 is its general circuit fault, the counterpart of P0251. No manufacturer using P0256 was found – Saab reports its two valves under other codes; the description follows CARB's circuit monitoring requirement and the A siblings.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Check engine light on
• Loss of power, limp mode

Common causes

• High Metering valve B open
• High Connector or wire to valve B open
• Low Engine module

Likelihood is a general estimate across vehicles; your make and model may differ.