OBD-II code · Powertrain (generic, extended)
P229F NOx Sensor Circuit Range/Performance Bank 1 Sensor 2
The downstream NOx sensor on bank 1 (after the SCR catalyst) returns implausible NOx readings during operation. Either the sensor is degraded or upstream chemistry is abnormal.
Is it safe to drive with P229F?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyNOx sensor aging
- PossibleLow SCR efficiency
- Less likelySensor element aged beyond calibration window
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–4 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Nox Sensor, Scr Catalyst
Related codes
- P229CFuel Pressure Regulator B Exceeded Learning Limits - Too Low
- P229DFuel Pressure Regulator B Exceeded Learning Limits - Too High
- P229ENOx Sensor Circuit (Bank 1 Sensor 2)
- P22A0NOx Sensor Circuit Low (Bank 1 Sensor 2)
- P22A1NOx Sensor Circuit High (Bank 1 Sensor 2)
- P22A2NOx Sensor Circuit Intermittent (Bank 1 Sensor 2)
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.