P23B0NOx Sensor Circuit Intermittent (Bank 1 Sensor 3)
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P23B0 is meant for a third NOx sensor on bank 1 whose circuit faults come and go instead of staying present, so the status the sensor module reports over CAN keeps toggling between valid and faulty. No manufacturer documents P23B0 publicly, and none publishes a threshold for it; GM's 2025 diesel table, which details several other sensor 3 codes, does not list it. HELLA's workshop guidance on NOx sensors names plug connections and wiring harmed by moisture, grime and road salt and recommends checking supply and bus communication – a good fit for a fault that keeps returning. CARB requires circuit faults on NOx sensors to be detected. P23AC is the steady circuit fault; P2204 and P22A2 are the intermittent codes of sensors 1 and 2. The MIL may go out and come back.
- What you may notice
- Check engine light that goes out and returns
- Sensor 3 value drops out briefly in live data
- Likely causes
- LikelyLoose or fretting terminal in a sensor 3 connector
- PossibleHarness rubbing or flexing near the exhaust, breaking contact under vibration
- PossibleMoisture entering a connector in wet weather
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.