P2AC2Intake Air O2 Sensor Reference Voltage Circuit High Bank 1
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2AC2 means the reference voltage at the intake oxygen sensor of bank 1 reads above its permitted range. A reference lead shorted to a supply wire or battery voltage in the harness, a lost ground on the sensor side or water in the connector are the usual triggers; a sensor with an internally damaged cell can produce the same picture. The intake sensor sits in a damp, oil-misted environment near the crankcase ventilation and EGR inlet, so connector corrosion deserves a look. No manufacturer publishes P2AC2 with thresholds; CARB's rule for comprehensive input components and Ford's patents on the sensor itself are the basis here. As with the other faults in this family, the ECM loses its measurement of recirculated exhaust and falls back to model-based or reduced EGR, which can raise NOx. P2AC1 is the low counterpart, P2AC6 bank 2.
- What you may notice
- Check engine light on
- EGR reduced, NOx emissions may rise
- Likely causes
- LikelyReference wire shorted to a supply or battery voltage wire
- PossibleMoisture or corrosion bridging pins in the sensor connector
- PossibleOpen ground on the sensor side
- 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: €0 – €350
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.