P2A3AO2 Sensor Positive Current Control Circuit High Bank 1 Sensor 3
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P2A3A means the voltage on the pump-current (positive control) lead of probe number three, bank 1, sits above its expected level. The usual culprit is contact with a supply: the heater feed runs in the same harness and connector, and moisture or heat damage at the plug can bridge the two. An offset pump current would falsify the lambda value, so the controller stops trusting it. P2A3A is not described by any manufacturer in public sources; Ford handles a short to battery on its front IP wires under P0132 instead. P2A38 is the open-circuit fault, P2A39 the low one, P2A3D the high fault on the return. The engine normally runs as before, but the lamp comes on and diagnosis starts with voltage checks at the connector.
- What you may notice
- Check engine light after repeated detection
- Sensor 3 reports an implausibly lean value
- Likely causes
- LikelyPump-current wire touching the heater feed in harness or plug
- PossibleWater or corrosion in the sensor connector under the car
- RareInternal short between heater and pump cell of the probe
- 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 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.