OBD-II code · Powertrain (generic, extended)
P225D NOx Sensor Performance - Signal Biased/Stuck Low (Bank 1 Sensor 1)
NOx Sensor Performance - Signal Biased/Stuck Low (Bank 1 Sensor 1): the component is electrically intact but its response does not match the command.
Is it safe to drive with P225D?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelySensor aged or condensate damaged
- Less likelySensor element aged beyond calibration window
- Less likelySensor element contaminated by oil, soot or coolant
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
- 1–3 h
- Emissions test
- Likely to fail
- Parts involved
- Nox Sensor
Related codes
- P225CNOx Sensor Performance - Signal Biased/Stuck High (Bank 1 Sensor 1)
- P225FNOx Sensor Performance - Signal Biased/Stuck Low (Bank 1 Sensor 2)
- P225ANOx Sensor Calibration Memory (Bank 1 Sensor 1)
- P225BNOx Sensor Calibration Memory (Bank 1 Sensor 2)
- P225ENOx Sensor Performance - Signal Biased/Stuck High (Bank 1 Sensor 2)
- P2260Secondary Air Injection System Control B Circuit High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.