P0255: Injection pump fuel metering control A intermittent (cam/rotor/injector), diesel
Injection pump A circuit intermittent
Severity: Severity not verified — if the car runs badly, have it inspected
The sources read define the code and its causes but do not say how urgent it is, so no urgency class is claimed. Get it checked, more so if the engine will not start or loses power.
P0255 in short
P0255 is a diesel-only code for an intermittent fault in the injection pump's fuel metering control A circuit. Damaged or corroded wiring and connectors are the main cause, then a bad fuel control sensor. Check the wiring before replacing the injection pump.
The computer drives a fuel control actuator on the injection pump and watches a sensor for the result.
P0255 sets when the circuit loses continuity from time to time. TroubleCodes.net warns the most common mistake is replacing the injection pump when the problem is an electrical connection.
Most likely causes
These are general causes for this code across vehicles. None is specific to one make or model.
Cause 1: Damaged or corroded wiring or connectors
Common general cause- Why it ranks here
- Both sources and the TroubleCodes.net page put wiring and connector faults first; circuit codes often come from poor connections rather than parts.
- What would change this
- Rises if a damaged or corroded connector is found. Falls if wiring and connectors test clean.
Cause 2: Defective fuel rack position sensor or fuel quantity actuator
Common general cause- Why it ranks here
- TroubleCodes.net lists the fuel control actuator and the metering sensor as the parts that must agree.
- What would change this
- Rises if the actuator and sensor signals disagree. Falls if they match.
Cause 3: Engine computer fault (rare)
Common general cause- Why it ranks here
- TroubleCodes.net lists the computer as a rare cause to check only after other causes.
- What would change this
- Rises only after wiring, actuator and sensor all test good.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: Look over the wiring and connectors at the injection pump and its fuel control actuator and sensor for damage, corrosion or a loose plug.
IfDamaged, corroded or loose wiring or a connector is found
It meansThe circuit fault is the likely cause.
IfWiring looks fine
It meansHave the actuator and sensor signals tested.
Step 2: Have a shop compare the signal sent to the fuel control actuator with the signal returned by the metering sensor, using a bidirectional scan tool.
Warning:The injection pump is on a high-pressure diesel fuel system, and fuel can spray at high pressure if a line or fitting is opened. Leave pump work to a diesel shop.
IfThe two signals do not agree
It meansThe actuator, sensor or pump is suspect.
Points to: Defective fuel rack position sensor or fuel quantity actuator
IfThe signals agree and the code returns
It meansA fault in the computer is possible but rare; recheck everything else first.
Symptoms
- Warning light on, sometimes
- Hard starting or no start
- Heavy tailpipe smoke
- Rough idle
- Weak acceleration and hesitation
- Worse fuel economy
How to fix
Step 1: With the engine off and cool, look at the visible wiring and plugs near the injection pump for chafing, corrosion or a loose connector.
On your vehicle
We don't have reviewed vehicle-specific evidence for P0255 yet. The causes and tests above apply across vehicles.
Related codes
Sources and review
- On-Board Diagnostic Trouble Codes (generic code title list)
- P0255 trouble code: injection pump A, rotor/cam, circuit intermittent
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error