P0257
Injection Pump Fuel Metering Control B Range/Performance (Cam/Rotor/Injector)
Diesel fuel injection
Generic OBD-II
High
What it means
P0257 means the "B" fuel metering control of the diesel injection pump is not performing within its expected range — the amount of fuel being metered does not match what the ECM commands. Because this directly affects fuel delivery, it can cause low power, rough running, hard starting, or stalling until the metering valve, wiring, or pump is repaired.
High
Can I keep driving? Limited — this diesel fuel-metering fault can cause low power, rough running, and in some cases stalling or hard starting, so repair promptly.
Common symptoms
What you'll notice
- Check-engine light on
- Reduced power and poor acceleration
- Rough running or unstable idle
- Hard starting or, in some cases, stalling
Common causes
Most likely first
- Faulty injection-pump fuel metering control valve ('B')Likely
- Damaged, corroded, or loose wiring/connector in the metering control circuitCommon
- Worn or failing injection pump affecting metering accuracyCommon
- Faulty engine control module (ECM) — least commonLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and check the metering control valve command versus actual with a scan tool.
- Inspect the metering-valve connector and wiring for damage, corrosion, or opens.
- Test the fuel metering control valve resistance/operation against spec; replace if faulty.
- If the valve and wiring are good, have the injection pump and ECM evaluated. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0257?+
Drive as little as possible. Fuel-metering faults can cause low power, rough running, or stalling, and continued running with poor metering can stress the injection system.
Can I just clear P0257?+
It clears, but a metering range/performance fault returns until the valve, wiring, or pump is repaired.
Related codes
Often seen with P0257
Read & clear P0257 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX