Injection Pump Fuel Metering Control A Malfunction (Cam/Rotor/Injector)
The P0251 code means the vehicle's onboard diagnostic system has detected: Injection Pump Fuel Metering Control A Malfunction (Cam/Rotor/Injector). This is a serious severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- hard
- Estimated cost
- $50 - $4,000+ (a fuel filter or supply-side restriction at the low end; wiring or connector repair in the middle; injection pump replacement at the top)
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Common Symptoms
- Check Engine Light on
- Hard starting or long cranking
- Rough running, low power, possible stalling
- Possible smoke on diesels
Probable Causes (Ranked by Likelihood)
- Injection pump fuel metering fault (cam/rotor/injector control) High
- Low fuel supply to the pump — filter, lift pump, restriction High
- Wiring or connector fault to the pump's metering control Moderate
- Failing injection pump Moderate
Step-by-Step Diagnostic Procedure
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This is a DIESEL injection-pump code: the computer cannot control fuel metering as commanded.
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Check the low-pressure supply first — fuel filter and lift pump. A starved pump sets metering faults while itself being healthy.
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Inspect wiring and connectors to the pump's metering control before condemning the pump.
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Injection pump replacement is the last step, not the first — supply and wiring faults produce identical codes.
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Meaning corroborated against this site's independently researched diesel-family pages for the same code (Duramax, Hino, Isuzu, Power Stroke — 4 independent families).
Frequently Asked Questions
What does P0251 mean?
The engine computer detected a malfunction in the injection pump's fuel metering control — the mechanism (cam, rotor, or injector control depending on pump design) that decides how much fuel is delivered. It is a diesel code; check fuel supply and wiring before suspecting the pump itself, because a starved or poorly connected pump sets the same code.
Is this the wastegate code some sites list?
No. P0251 is sometimes mislabeled as a turbo wastegate solenoid code, but the wastegate solenoid codes are the P0243-P0249 range. P0251 opens the injection pump fuel metering block (P0251-P0260), which is why it appears on diesel trucks and equipment rather than turbocharged gas cars.
Sources
This page is built from documented references. Verify against your own service info before repair work.
P0251 on Diesel, EV & Equipment
The same code ID appears across other engines and platforms. The diagnostic flow varies by manufacturer — these are the platform-specific breakdowns:
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