P0255
UniversalInjection Pump Fuel Metering Control A Intermittent (Cam/Rotor/Injector)
High SeverityThis code indicates an intermittent fault with the fuel metering control circuit 'A' within the injection pump. This can lead to inconsistent fuel delivery, affecting engine performance and potentially causing the vehicle to stall or run rough.
⚠️ Before You Begin (Safety First)
Always exercise caution when working with vehicle fuel systems. Fuel is highly flammable, and high-pressure fuel systems can cause serious injury. Always wear appropriate personal protective equipment, disconnect the battery before beginning any work, and ensure proper ventilation.
Common Symptoms
- Check Engine Light illuminated
- Engine may crank but not start
- Engine misfires or runs rough
- Reduced engine power or acceleration
- Engine stalls unexpectedly
- Poor fuel economy
- Excessive smoke from the exhaust (especially in diesel applications)
Common Causes
- Faulty fuel metering control valve (FMCV) or solenoid
- Wiring harness issues (chafed, corroded, or open circuit)
- Poor electrical connection at the injection pump or FMCV
- Intermittent fault within the injection pump itself
- Contaminated fuel system
- Faulty engine control module (ECM) (less common)
Frequently reported on: Ford F-Series Super Duty (Diesel) 2003-2007, Chevrolet Silverado/GMC Sierra 2500/3500 HD (Duramax Diesel) 2004-2010, Dodge Ram 2500/3500 (Cummins Diesel) 2006-2012, Mercedes-Benz Sprinter Vans (Diesel) 2008-2014, Volkswagen TDI models 2004-2008
Diagnostic Steps
- Check for any other related diagnostic trouble codes (DTCs).
- Visually inspect the wiring harness and connectors for the injection pump and fuel metering control valve for damage, corrosion, or loose connections.
- Ensure the battery voltage is adequate and the charging system is functioning correctly.
- If accessible, inspect the fuel metering control valve for proper operation (though often requires specialized tools).
- Check fuel pressure and fuel quality if possible.
- Clear the code and test drive the vehicle to see if the fault returns, noting any specific conditions when it recurs.
👨🔧 When to Call a Professional
If you lack experience with diesel fuel systems, specialized diagnostic tools, or the issue persists after basic checks, it is highly recommended to consult a certified professional diesel mechanic. Incorrect diagnosis or repair of high-pressure fuel components can lead to further damage or safety hazards.
Commonly Asked Questions
What does "Intermittent" mean in P0255?
"Intermittent" means the fault is not constant; it appears and disappears, making it harder to diagnose. The problem might only occur under specific driving conditions, like certain engine temperatures or loads.
Can P0255 cause my engine to stall?
Yes, an intermittent fault in the fuel metering control can lead to inconsistent fuel delivery, which can cause the engine to misfire, run very rough, or even stall unexpectedly, especially during acceleration or idling.
Is it safe to drive with a P0255 code?
It is generally not recommended to drive with a P0255 code, especially if symptoms like stalling, significant power loss, or rough running are present. This issue directly affects fuel delivery and engine performance, potentially leaving you stranded or causing dangerous situations.
How can I test the fuel metering control valve?
Testing the fuel metering control valve often requires a professional scan tool to command it on and off, or a multimeter to check for proper resistance and voltage signals. Due to its location within or near the high-pressure injection pump, specialized knowledge is typically needed.
What's the difference between 'Control A' and 'Control B' in fuel metering codes?
In most systems, 'Control A' refers to the primary fuel metering control circuit or valve, while 'Control B' would refer to a secondary circuit if the system uses one, or a different bank of cylinders in a V-engine configuration if applicable to injectors. For injection pump systems, 'A' usually indicates the main fuel quantity control.