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DTC codes / P02xx · Fuel and air metering (injector circuits) / P0255

P0255Injection Pump Fuel Metering Control 'A' Intermittent (Cam/Rotor/Injector)

P0255 means the engine computer has detected an intermittent fault in the fuel metering control circuit for injection pump control 'A', which is the solenoid or actuator that regulates how much fuel the pump delivers on a diesel engine. The circuit works for some drive cycles and then drops out or glitches, so the computer cannot trust the fuel quantity signal and logs the code once the fault repeats.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyProfessional
AreaFuel and air metering (injector circuits)

Symptoms you may notice

  • Often no symptoms besides the warning light, because the fault is intermittent and the pump still meters fuel correctly most of the time
  • Momentary loss of power or a stumble under acceleration when the metering circuit cuts out
  • Rough idle or surging that comes and goes, especially when the engine is cold or the wiring is disturbed
  • Hard starting or a crank-no-start condition on the occasions the circuit fails during cranking
  • Reduced fuel economy or black smoke during the moments the pump defaults to a limp fuel quantity
  • A stored code that clears itself after several clean drive cycles and then returns

Common causes, most likely first

  1. Chafed, corroded or loose wiring and connector pins between the engine computer and the injection pump metering solenoid
  2. A failing fuel metering solenoid or actuator coil inside the injection pump that opens intermittently when hot
  3. Water or debris in the pump connector causing an unstable electrical contact
  4. A weak or intermittent ground shared by the pump circuit and the engine computer
  5. Internal pump wear or a sticking metering valve that makes the actuator draw irregular current
  6. A failing engine computer driver for the metering circuit, which is rare but does happen after long-term heat cycling

How to diagnose and fix it

  1. Scan all modules and record freeze-frame data for P0255, then clear the code and road test to confirm it returns under the same conditions
  2. Inspect the injection pump metering solenoid connector and the full harness run for chafing, corrosion, pushed-back pins and tight bends
  3. Measure the resistance of the metering solenoid coil cold and again after the engine reaches operating temperature, comparing the two readings
  4. Back-probe the circuit with a multimeter or oscilloscope while wiggling the harness to catch an intermittent open or short
  5. Check the ground circuit from the pump and computer to the battery negative with a voltage drop test under load
  6. If the wiring and coil test clean, command the metering actuator with a scan tool and watch for a response that drops out
  7. Replace the faulty solenoid, pump assembly or computer driver only after the electrical tests prove the fault is inside that component

Intermittent codes hide in the harness

  • An intermittent metering code is far more often a wiring or connector problem than a failed injection pump, so the harness deserves a full wiggle test before any pump is condemned.
  • Heat and vibration cause the fault to appear only when the engine is hot or the vehicle is moving, which means a cold static resistance check can pass and mislead you.
  • A sticking metering valve inside the pump can mimic an electrical fault by making the solenoid current erratic, so current waveform testing separates the two.
  • The code can set from a single glitch during cranking and never return for weeks, so a clean scan after clearing does not prove the fault is gone.
  • Shared grounds and power feeds with other engine sensors can pull the metering circuit voltage down and set P0255 alongside unrelated codes.

Can I keep driving with P0255?

You can usually drive to a workshop because the fault is intermittent, but avoid heavy acceleration and long trips until it is diagnosed. If the engine stumbles, surges or loses power repeatedly, stop driving and have the circuit inspected before the pump defaults to a limp mode.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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