P23ABNOx Sensor Processor Performance (Bank 1 Sensor 3)
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- A NOx sensor is a smart part: the probe in the exhaust is wired to a small control unit with its own processor, which runs the heater, evaluates the cell currents and reports over CAN. P23AB means that this electronics in sensor 3 of bank 1 – usually the one behind a second SCR catalyst – reports an internal error or fails its self-checks. No manufacturer documents P23AB publicly. Ford's 2023 diesel OBD summary shows what such checks contain for its front sensor: RAM failure and ROM or EEPROM checksum errors, reported there under P2200. CARB requires NOx sensors to be monitored for faults that make them unusable for the SCR checks. P06EA and P06EB are the processor codes of sensors 1 and 2. Repair normally means a new sensor.
- What you may notice
- Check engine light on
- Sensor 3 values missing or frozen in live data
- SCR or emissions warning on the display
- Likely causes
- LikelyInternal electronics of the sensor 3 control unit defective
- PossibleSupply voltage dips or poor ground resetting the sensor electronics
- RareSensor control unit damaged by heat or water ingress
- 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: €200 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.