The downstream oxygen sensor on bank 1 reads high voltage for too long. The driver often notices only the engine light.
Likely causes, most common first
- Rich mixture
- Faulty oxygen sensor
- Short to voltage in the wiring
- Fuel or oil contamination of the sensor
Parts usually involved
- Oxygen sensor
- Sensor connector
Test before you replace
Check for a rich mixture first, then test the sensor signal and wiring for voltage.
General guidance for generic OBD2 codes. Always follow the maker's procedure for the car in front of you.