OBD-II code · Powertrain (generic, extended)
P2203 NOx Sensor Circuit High (Bank 1)
The NOx sensor signal on bank 1 is above the upper limit — short to supply, open ground, or a sensor that failed high. SCR control runs in default mode.
Is it safe to drive with P2203?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySignal wire shorted to supply
- PossibleSensor failed high
- Less likelyConnector pins corroded - high contact resistance
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
- Often, with basic tools
- Typical labour
- 0.5–2.5 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Nox Sensor, Nox Sensor Wiring
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.