P0043
HO2S Heater Control Circuit Low Bank 1 Sensor 3
Heater control voltage of the bank 1, sensor 3 oxygen sensor is below the expected range — short to ground or low-resistance fault.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Heater wiring shorted to groundCommon
- Connector pins corroded - high contact resistanceLess likely
- Harness chafing through insulationLess likely
Parts involved
- Oxygen Sensor B1s3 Heater
- Heater Wiring
P0043 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.