P0255
UniversalInjection Pump Fuel Metering Control A Intermittent (Cam/Rotor/Injector)
The engine computer has detected an intermittent condition in the injection pump's Fuel Metering Control A, associated with the cam, rotor, or injector as applicable to the vehicle's design. This control helps regulate fuel delivery. If its signal or operation cuts in and out, the engine may not receive fuel consistently, but the code alone does not prove that the pump or another specific part has failed.
⚠️ Before You Begin (Safety First)
If the engine stalls, loses power severely, or runs unpredictably, pull over safely and arrange diagnosis rather than continuing to drive in traffic. Do not loosen or open injection-pump or fuel-injection lines; fuel systems can operate at hazardous pressure. Have a qualified technician handle fuel-system tests requiring disassembly.
Common Symptoms
- There may be no noticeable symptoms if the intermittent condition is brief or does not affect fuel delivery enough to change engine operation.
- The engine may hesitate, stumble, or run roughly if fuel metering becomes inconsistent.
- Starting may become difficult or the engine may stall if the control condition interrupts fuel delivery.
- Reduced power or inconsistent acceleration may occur when the engine cannot maintain the requested fuel delivery.
Common Causes
- A loose, corroded, or damaged connector may intermittently interrupt the fuel metering control connection.
- Chafed, broken, or poorly connected wiring, or an unstable power or ground connection, may disrupt the control circuit.
- The fuel metering control actuator or its related electrical circuit may operate intermittently.
- A fault involving the injection pump's cam or rotor, or an injector-related control or function, may contribute, depending on the vehicle's design.
- An intermittent condition elsewhere in the control system may produce the detected behavior; the code does not identify a failed part by itself.
Diagnostic Steps
- Note any symptoms and whether they occur during starting, idling, or acceleration; this context can help a technician reproduce the intermittent condition.
- With the engine off, visually inspect accessible wiring and connectors related to the injection pump metering control for looseness, corrosion, or visible damage. Do not force connectors or probe terminals without vehicle-specific instructions.
- If a suitable scan tool is available, record other codes and any available freeze-frame information before clearing codes; related information may help identify when the condition occurred.
- Do not open fuel lines or attempt internal injection-pump, cam/rotor, or injector testing at home. Ask a qualified technician to perform the required circuit and fuel-system checks.
When to Call a Professional
A technician can check stored and pending codes and relevant scan data, then inspect the control circuit and connectors for intermittent contact, damaged wiring, or poor power or ground. Testing should follow the vehicle's model-, year-, and engine-specific service information. If the circuit checks out, further pump, cam/rotor, or injector-related diagnosis may be needed before deciding whether any component requires repair or replacement.
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Commonly Asked Questions
Does P0255 prove that the injection pump needs replacement?
No. It reports an intermittent condition in Fuel Metering Control A. Wiring, connectors, power or ground, the control actuator, or related pump or injector functions may need investigation before any part is condemned.
What does “intermittent” mean in this code?
The monitored control signal or operation was not consistently within the system's expected behavior. The issue may come and go, so inspecting scan information and connections can be useful even if the engine currently feels normal.
Can I keep driving with P0255?
That depends on how the vehicle runs. If it stalls, has severe power loss, or behaves unpredictably, stop in a safe place and arrange service. If it runs normally, seek diagnosis promptly because the condition may return.
Can I inspect the fuel system myself?
You can visually check accessible wiring and connectors with the engine off, but do not loosen fuel lines or open the injection system. Exact checks depend on the vehicle, and pressurized fuel-system work should be left to a qualified technician.
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