P2245
O2 Sensor Reference Voltage Circuit Low (Bank 1 Sensor 1)
The reference voltage feeding the bank 1, sensor 1 wide-band oxygen sensor is below the lower threshold. Often a short to ground in the wiring or a failed reference output stage.
- 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.
- Reference line shorted to groundCommon
- ECU reference output failedLess likely
- Connector pins corroded - high contact resistanceLess likely
Parts involved
- Oxygen Sensor Upstream
- Oxygen Sensor Wiring
P2245 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.