P239EO2 Sensor Out of Range During Deceleration (Bank 1 Sensor 2) - Duplicate Listing of P232F
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P239E carries in common code lists exactly the same wording as P232F: a downstream oxygen sensor on bank 1 reading outside its expected window while fuel is cut on deceleration. No manufacturer, OBD summary or service bulletin on record uses P239E, and no source gives it a meaning of its own. The documented version is P232F, which GM applies to the 2023 6.6L L5P Duramax, comparing sensor 2 with sensor 1 in overrun (window +3.01 to −3.18 %, Type B). P239E is therefore best treated as a duplicate listing. Should a scan tool show it, read the maker's own code definition and freeze-frame data, then test the rear sensor as for P232F; CARB requires a rich-to-lean check of rear sensors during fuel shut-off.
- What you may notice
- MIL on without noticeable driving change
- Code text in the scan tool contradicts the manufacturer's documentation
- Likely causes
- LikelyScan tool code table showing the duplicate number instead of the maker's code
- PossibleAged or drifting rear oxygen sensor on bank 1
- RareExhaust leak ahead of the rear sensor
- 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: €0 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.