Cause
Worn injection pump metering assembly
The high pressure pump's metering elements — pistons, bores and the control valve — worn to the point where the pump can no longer reach or hold commanded rail pressure. It is the failure at the end of the fuel pressure diagnosis rather than the start of it, and the order matters because a restricted filter and a weak lift pump imitate it exactly while costing a fraction as much.
These pumps are lubricated by the fuel they pump, which is what makes their wear self-accelerating and what connects it to everything upstream. Water displaces that lubricating film; debris scores the bores; running the rail short of pressure worsens both. A pump that failed early was usually failing because of something that is still in the tank.
Wear shows under demand rather than at idle. The symptom is a shortfall that appears under load or at high engine speed and disappears at light throttle, because a worn pump can still meet a small demand.
Check the low-pressure feed while the fault is present before condemning the pump. A pump starved by a blocked filter behaves identically from the module's point of view, and debris from a genuinely failed pump circulates through the whole system — so a replacement fitted without flushing the rail, lines and injectors is fed its own predecessor's wreckage.
Typically specialist work. Needs equipment or training most home workshops do not have.
Some of these codes mean you should stop driving
4 of the 8 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (8)
Codes where this is a likely explanation first, rather than merely a possible one.
- P0251 Injection Pump Fuel Metering Control A — Cam/Rotor/Injector Likely for this code Stop driving High
- P0252 Injection Pump Fuel Metering Control A Range/Performance (Cam/Rotor/Injector) Likely for this code Stop driving High
- P0256 Injection Pump Fuel Metering Control B (Cam/Rotor/Injector) Likely for this code Stop driving High
- P0257 Injection Pump Fuel Metering Control B Range/Performance (Cam/Rotor/Injector) Likely for this code Stop driving High
- P2672 Injection Pump Timing Offset Likely for this code High
- P009E Fuel Pressure Relief Control Performance/Stuck Off Moderate
- P00C6 Fuel Rail Pressure Too Low - Engine Cranking Bank 1 High
- P016F Closed Loop Fuel Pressure Control At Limit - Pressure Too Low High
Information, not instruction
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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.
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