P0404: Exhaust Gas Recirculation "A" Control Circuit Range/Performance
P0404 means Exhaust Gas Recirculation "A" Control Circuit Range/Performance. The EGR valve is not reaching the position the engine computer commanded. The signal is inside its electrical limits, but it does not make sense compared with what the module expects from other sensors or from engine conditions (a "range/performance" fault). The part is often working electrically but reporting a wrong or implausible value.
Can I keep driving? Drivable with care. Diagnose soon: performance, economy or other components can be affected.
Common symptoms
- Check engine light on
- Possible rough idle or knocking
- Failed emissions test
Possible causes
- Faulty EGR valve or solenoid
- Wiring or connector fault
- Faulty EGR position sensor
- Engine computer driver fault (rare)
How to diagnose P0404
- Inspect the connector and wiring.
- Check power, ground and signal circuits.
- Command the valve on a scan tool and confirm it responds.
What the code means, digit by digit
Generic codes have the same definition on every OBD-II vehicle (petrol cars from model year 1996 in the US, 2001 in the EU; diesels later). Manufacturers can add their own enhanced codes; those are not listed here.
Related codes
General guidance only. Fault codes describe what the engine computer saw, not which part failed: confirm with testing before replacing parts, and follow the vehicle's service information.