P0251: Injection Pump Fuel Metering Control A — Cam/Rotor/Injector
Do not keep driving
Expect poor power, rough running or a no-start. Have it diagnosed by someone equipped for diesel injection work rather than driven on, and expect the pump's internal condition to be assessed before replacement is proposed.
What this code means
A fault in the primary fuel metering control inside the injection pump. On mechanically timed diesel systems the pump itself decides how much fuel each stroke delivers, using a cam or rotor assembly under electronic control — so a metering fault is internal to the pump rather than out in the wiring. That distinction matters commercially: injection pumps are expensive, and confirming the fault properly before condemning one is worth real money.
Likely causes
Start here
- Worn injection pump metering assembly · specialist
- Fuel contamination · specialist
- Restricted fuel filter · easy
- Failed fuel metering control solenoid · specialist
Less common
- Water in fuel tank · moderate
- Weak low pressure lift pump · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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