P2238
O2 Sensor Pumping Current Circuit Low (Bank 1 Sensor 1)
Pumping current at the bank 1 sensor 1 wide-band lambda probe is below the lower limit — short to ground or sensor at end of life.
- 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 line shorted to groundCommon
- Wide-band sensor agedPossible
- Connector pins corroded - high contact resistanceLess likely
Parts involved
- Oxygen Sensor Wideband
- Oxygen Sensor Wiring
P2238 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.