P042EEGR A Control Stuck Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Exhaust gas recirculation (EGR) routes part of the exhaust back into the intake to lower combustion temperature and NOx. P042E means the position-controlled EGR valve A is more open than commanded and cannot be closed. GM's diesels of 2016/17 set it when the valve stays too far open despite maximum closing duty (about 1–8 s); the 2018 tables check after switch-off whether it is below 5 % within 2 s – both with MIL on the first trip. Ford petrol engines compare the position with limits for 4 s, Ford diesels a deviation above 15 % for 25 s. Too much EGR causes rough idle, stalling and smoke; EGR control is switched off.
- What you may notice
- Check engine light on (GM after one trip)
- Rough idle, stalling, starting problems
- Loss of power, possibly limp mode
- Diesel: smoke, higher soot load
- Likely causes
- LikelyValve or disc coked, does not close
- PossibleActuator motor, gear or return spring faulty
- PossiblePosition sensor in the valve reads wrong
- RareWeak supply to the drive or connector fault
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €150 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.