What it means
The negative pump current control of the intake air oxygen sensor on bank 2 reports a circuit low condition. Wide-band lambda regulation on the intake side is impaired.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The bank 2 intake air oxygen sensor is a wideband sensor that helps the module assess oxygen in the intake stream for lambda control. The module monitors its negative pump-current control circuit and sets P2AF0 when that circuit reads lower than expected, impairing intake-side mixture regulation.
Common causes
Most likely first.
- Pump current wire shorted to ground
- Internal short in pump cell
- Connector pins corroded - high contact resistance
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
How to diagnose it
- Record freeze-frame data and compare bank 2 sensor readings with the other bank to see when the low-circuit fault appears.
- Inspect the bank 2 intake oxygen sensor connector and harness for corrosion, damage, or wiring pinched against ground.
- Check connector pin fit and corrosion, since poor contact can interfere with the pump-current circuit.
- With the sensor disconnected, test the negative pump-current wire for an unintended path to ground using the manufacturer's wiring diagram.
- If wiring and connections are sound, test the sensor pump cell and circuit response using the manufacturer's procedure to check for an internal short.
Common fixes
- Clean or repair corroded bank 2 sensor connector terminals.
- Repair the negative pump-current wire where it is shorted to ground.
- Replace the bank 2 intake air oxygen sensor if its pump cell is internally shorted.
Can I keep driving?
You can usually drive gently if the engine runs normally, but avoid hard acceleration and prolonged trips because mixture control and fuel economy may suffer. Arrange diagnosis soon, especially if the engine runs roughly or an emissions test is due.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.