P23E5EGR C Control Stuck Open
- 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
- P23E5 means EGR valve C stays open although it is commanded closed. The 2018 GM diesel calibration decides the A-side code P042E like this: once the driver is switched off, the return spring should bring the valve to its closed default within 2 s; if the measured position is still above 5 % after that, the code sets at once as Type A, MIL on the first trip. Comparable logic would suit valve C. Too much exhaust gas at idle or under load causes rough running, misfire, stalling and, on diesels, smoke, which is why such faults are rated urgently. Carbon build-up holding the flap open is the usual cause; a broken spring or jammed linkage are others. No manufacturer documents P23E5 publicly. Stuck closed: P23E6, excessive flow: P23E8.
- What you may notice
- Rough idle or stalling
- Misfire and lack of power
- Smoke on diesel engines
- Warning lamp on the first trip
- Likely causes
- LikelyCarbon deposits holding valve C open
- PossibleBroken return spring in valve C
- RareJammed shaft or linkage
- 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: €100 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.