P04FDEGR Actuator A Control Processor Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- Exhaust gas recirculation (EGR) routes part of the exhaust back into the intake to lower combustion temperature and NOx. Some EGR actuators have their own electronics (smart actuators), with position control inside the actuator and communication with the engine module by bus or PWM. P04FD means the actuator reports an internal processor or electronics fault, or its self-test failed. CARB does not require such internal faults to be reported, so the code is a voluntary detail. Volvo and Mack trucks with turbocompound document it with false triggers fixed by engine software. The actuator then goes to its default position and EGR is off.
- What you may notice
- Check engine light on
- Reduced power possible
- Higher NOx
- Likely causes
- LikelyEngine or actuator software (false trigger)
- PossibleElectronics in the EGR actuator faulty (heat, moisture)
- PossibleActuator supply or ground unstable
- RareValve stiff, causing a control fault in the actuator
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.