P2AC3Intake Air O2 Sensor Reference Voltage Circuit/Open Bank 2
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2AC3 is the open circuit fault in the reference voltage lead of the intake air oxygen sensor assigned to bank 2. A second intake sensor only exists where each cylinder bank has its own intake or EGR path, for example on V engines with two separate charge air routes; engines with a single sensor use the bank 1 code P2ABF. No manufacturer has published P2AC3 or a vehicle using it. Technically the check works as on bank 1: if the reference wire to the sensing cell is interrupted, the ECM can no longer operate the cell and receives no usable oxygen value, so EGR on that bank runs without feedback. Wiring routed close to the hot turbo or exhaust of the second bank is the first place to look. P2AC4 is the plausibility fault, P2AC5/P2AC6 low/high.
- What you may notice
- Check engine light on
- EGR on bank 2 reduced or uncontrolled
- Likely causes
- LikelyBroken reference wire or loose terminal at the bank 2 sensor
- PossibleHarness damaged by heat near the bank 2 turbocharger or exhaust
- RareSensing cell of the bank 2 intake oxygen sensor internally open
- 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.