P22B7O2 Sensor Pumping Current Trim Circuit High (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
- P22B7 is, going by its title, the high fault on the trim circuit belonging to bank 1's downstream wide-band probe. In GM's diesel tables (2016, 2018 and 2025 group 04) the code is a ceiling test on the oxygen value of the second NOx sensor: the 2016 table flags readings above 24 %, which is more oxygen than fresh air holds, in 100 of 200 samples. The test runs only while exhaust back-pressure stays below its limit, no exhaust brake is active and no NOx sensor pressure fault is pending; GM rates it Type B, two trips. GM bulletin 21-NA-149 lists it for the 3.0 Duramax LM2 alongside harness chafing. No public source gives a trim-resistor threshold. P22B5 is the open, P22B6 the low case, P22C4 bank 2. The lamp lights.
- What you may notice
- Check engine light
- Downstream oxygen value above 21 % in live data
- Likely causes
- LikelyFaulty downstream NOx/oxygen sensor reporting excess oxygen
- PossibleChafed engine harness affecting the sensor lines (GM 3.0 LM2)
- RareTrim or signal wire shorted to a voltage source
- 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: €50 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.