The heater in the downstream oxygen sensor on bank 1 has a circuit fault. The driver usually sees only the engine light.
Likely causes, most common first
- Failed heater in the sensor
- Blown fuse
- Damaged wiring under the car
- 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.