P0257 code meaning
Injection Pump Fuel Metering Control B Range/Performance (Cam/Rotor/Injector)
Powertrain system Generic code P02xx codes Check engine light
What P0257 means
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.
P0257 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 8 hours
- Clears after repairAfter a drive cycle
Symptoms of P0257
- Check engine light on
- Power derate
- Hard starting, low rail pressure when cranking
- Jerking under load
Common causes of P0257
- Most likelyRail pressure or metering target not reached (leak, relief valve open)
- PossiblePoor low-pressure supply (filter, lift pump, air)
- PossibleMetering actuator or pumping element worn
- Less likelySoftware or diagnostic level
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Fuel metering actuator bHigh pressure fuel pumpActuator wiringFuel rail pressure relief valve
What each part of P0257 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 2 | Area: fuel and air metering (injector circuit). |
| 57 | The exact fault in that area. |
What to do next
- Note P0257 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0257
What does P0257 mean?
P0257 means "Injection Pump Fuel Metering Control B Range/Performance (Cam/Rotor/Injector)". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P0257?
Drive gently and only to a workshop. With P0257 the car can go into limp mode (reduced power) to protect itself.
Will P0257 fail an emissions test?
Yes, it can. P0257 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0257 to fix?
Difficulty: hard. A typical repair takes 1 to 8 hours of work. This is a job for a workshop.
Will P0257 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.