OBD-II code · Powertrain (generic, extended)
P22FD NOx Sensor Performance Slow Response High to Low Bank 1 Sensor 2
The downstream NOx sensor on bank 1 (post-SCR) responds too slowly when NOx levels fall after a reductant injection event. The control unit measures the time between commanded reductant dose and the resulting NOx drop and finds it exceeds the diagnostic threshold, indicating an aged sensor element.
Is it safe to drive with P22FD?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyNOx sensor element aged or thermally damaged
- PossibleSCR efficiency reduced (catalyst aged or contaminated)
- Less likelyReductant injector dosing drift
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
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–2 h
- Emissions test
- Likely to fail
- Parts involved
- Nox Sensor Post Scr B1, Scr Catalyst
Related codes
- P23C0NOx Sensor Performance Slow Response High to Low Bank 1 Sensor 3
- P22FANOx Sensor Performance - Slow Response High to Low (Bank 1 Sensor 1)
- P22FBNOx Sensor Performance - Sensing Element (Bank 1 Sensor 1)
- P22FCNOx Sensor Performance - Slow Response Low to High (Bank 1 Sensor 2)
- P22FENOx Sensor Sensing Element Bank 1 Sensor 2
- P22FFSCR NOx Catalyst Inlet Temperature Too Low
- P2300Ignition Coil A Primary Control Circuit Low
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.