P23ACNOx Sensor Circuit (Bank 1 Sensor 3)
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P23AC is the general electrical fault reported for NOx sensor 3 on bank 1. The sensor's own control unit watches the leads between its electronics and the ceramic probe and tells the engine computer over CAN whether a measuring circuit is open or shorted; the user manual of Drivven's NOx sensor module kit, published by NI, lists these status states for the NOx and O2 circuits. No manufacturer documents P23AC publicly. For its front sensor, Ford's 2023 diesel summary sets P2200 when the probe lines Vs, COM, Ip1 or Ip2 short to battery or ground. CARB requires NOx sensor monitoring to catch broken circuits and readings outside the possible range. More specific sensor 3 codes run from P23AD to P23B0; P2200 and P229E are sensors 1 and 2. Without a valid signal the final SCR check stops.
- What you may notice
- Check engine light on
- No NOx reading from sensor 3 in live data
- SCR system warning
- Likely causes
- LikelyLead between probe and sensor control unit damaged by heat or chafing
- PossibleCorroded or loose terminals at the sensor 3 connectors
- PossibleProbe or sensor electronics failed internally
- 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: €50 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.