Powertrain, generic · Fuel and air metering (injector circuit)

P0257 Injection Pump Fuel Metering Control B Range/Performance (Cam/Rotor/Injector)

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

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. P0257 is the functional fault of actuator B: the metering does not achieve its target. It is documented on Mack and Volvo heavy-duty common-rail diesels of 2018–2020 together with rail pressure codes (P0087, P016F, P228F) and P2A17/P2A1F; the cause can lie outside the actuator, for example an electronic pressure relief valve stuck open, a leak or poor low-pressure supply, so those faults are fixed first. Engine power may be derated.

Likely causes

Rail pressure or metering target not reached (leak, relief valve open)
Poor low-pressure supply (filter, lift pump, air)
Metering actuator or pumping element worn
Software or diagnostic level

Symptoms

  • Check engine light on
  • Power derate
  • Hard starting, low rail pressure when cranking
  • Jerking under load

Repair estimate

DifficultyHardWorkshop job
Parts and labour€150–4,000
Time1–8 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fuel metering actuator bhigh pressure fuel pumpactuator wiringfuel rail pressure relief valve

Related codes

P0252P0256P0258P2A17P2A1FP0087

References: law.cornell.edu, static.nhtsa.gov, static.nhtsa.gov.