P2A03O2 Sensor Circuit Range/Performance Bank 2 Sensor 1
- 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
- Bank 2 is the cylinder bank that does not contain cylinder 1, so P2A03 only occurs on V or flat engines; sensor 1 is the oxygen sensor ahead of that bank's converter used for fuel control. The fault is the bank-2 counterpart of P2A00: the sensor delivers a signal, yet fuel control cannot close the loop with it or keep it closed. In the Saab 9-4X (GM V6, LF1/LFW), P2A03 is logged when bank 2's fuel control loop is still reported open 30 s after the enabling conditions are met, as a two-trip Type B fault. GM's 2018 tables list P2A03 in the fault group for bank 2, sensor 1, which holds back the monitors that depend on that sensor. CARB demands detection when a sensor keeps the fuel system out of closed loop. Consumption and emissions of that bank rise while the loop is open.
- What you may notice
- Check engine light on
- Higher fuel consumption
- Rough idle or exhaust odour
- Failed emissions inspection
- Likely causes
- LikelyBank 2 front sensor aged or poisoned, too slow to reach closed loop
- PossibleSensor heater weak or wiring with high resistance, sensor stays too cold
- PossibleExhaust leak at the bank 2 manifold ahead of the sensor
- RareReal mixture problem on bank 2 (injector, vacuum leak) the sensor reports correctly
- 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: €80 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.