The heater inside the upstream oxygen sensor on bank 1 has a circuit fault. The sensor takes longer to work after a cold start, and consumption may rise.
Likely causes, most common first
- Failed heater in the sensor
- Blown fuse or relay
- Open or damaged wiring
- Corroded connector
Parts usually involved
- Oxygen sensor
- Fuse
- Sensor connector
Test before you replace
Measure heater resistance and check for power and ground at the connector.
General guidance for generic OBD2 codes. Always follow the maker's procedure for the car in front of you.