P2AF0
Intake Air O2 Sensor Negative Current Control Circuit Low Bank 2
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.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
Common causes
Ordered by how often each turns out to be the cause.
- Pump current wire shorted to groundCommon
- Internal short in pump cellPossible
- Connector pins corroded - high contact resistanceLess likely
Parts involved
- Intake Air O2 Sensor B2
- Wiring Harness
- ECM
P2AF0 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.