P0255 Injection Pump Fuel Metering Control A Intermittent (Cam/Rotor/Injector)

P0255 indicates intermittent injection pump fuel metering control A. The metering control signal or feedback drops out only under some conditions.

Code details

Generic OBD-II · P0

System: Fuel / Air
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not clear intermittent fuel metering faults without stressing the connector and reproducing the signal dropout.

Symptoms of P0255

Check-engine light on, sometimes with rough or uneven running.
Hesitation, surging, or a noticeable change in fuel economy.
Occasionally hard starting or a smell of unburnt fuel.

Common causes of P0255

A failing or contaminated sensor (MAF, MAP, oxygen or air-fuel sensor).
Intake or vacuum leaks, or an exhaust leak near an upstream sensor.
Wiring, connector, or fuel-delivery problems that skew the reading.

Useful checks before replacing parts

Graph metering command, pressure feedback, pump feedback, RPM, load, and system voltage while repeating freeze-frame conditions.
Inspect pump connector locking, terminal tension, harness rub points, heat sensitivity, fuel contamination, and intermittent power or ground faults.
Check whether the fault occurs during vibration, hot operation, heavy load, start attempts, or after fuel-system service.

Related OBD-II codes

These nearby fuel / air entries can help compare wording and pin down the fault area.