P232FO2 Sensor Out of Range During Deceleration (Bank 1 Sensor 2)
- 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
- P232F checks the downstream oxygen signal of bank 1 while fuel is cut on deceleration and the exhaust holds almost pure air. GM uses it on the 2023 6.6L L5P Duramax (Silverado HD, Sierra HD): the O2 value of sensor 2, the downstream NOx sensor, is compared with that of sensor 1 once the latter is stable in overrun; if the filtered difference leaves the window of +3.01 % to −3.18 %, a Type B fault is stored. The test runs only while P2297 is being evaluated and after 30 g of air have passed since. CARB requires rear-sensor monitoring and, where a full check is not feasible, at least a rich-to-lean check during fuel shut-off. Ford tests its rear petrol sensor in overrun too but files results under P013A, P013E or P2270. Code lists give P239E the same title. Causes are a drifting sensor, an exhaust leak or wiring faults.
- What you may notice
- Check engine light on
- Usually no change in driving behaviour
- MIL only after two trips with the fault (GM Type B)
- Likely causes
- LikelyDownstream sensor drifting or aged (on GM diesels the O2 signal of NOx sensor 2)
- PossibleExhaust leak near the downstream sensor
- PossibleDamaged sensor wiring or connector (chafing, corrosion)
- RareLeaking injector or upstream sensor fault distorting the overrun comparison
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · 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.