P0404EGR A Control Circuit Range/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. P0404 is the function check of the valve drive: on valves with a position sensor the module compares commanded and actual position, and a persistent deviation means the valve sticks, is coked or its drive is too weak (GM diesel 2018 above 10 %, GM petrol 2004 above 15 %, both MIL after two trips). Ford calls it control stuck. Saab's V6 diesel deviates and uses P0404 for a short to positive. EGR control is then switched off and the valve de-energised.
- What you may notice
- Check engine light on
- EGR deactivated
- Rough idle or jerking if the valve hangs open
- Diesel: possibly reduced power
- Likely causes
- LikelyValve coked or stiff
- PossibleValve drive (motor, gear) worn
- PossiblePosition sensor in the valve inaccurate
- RareSupply voltage too low or ground fault
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €100 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.