The O2 sensor or ECM can’t adjust air to fuel ratio as it’s supposed to even when the engine is running.
- Second O2 sensor in bank 1 is faulty
- Short, open or broken wire in O2 sensor circuit
- Exhaust leak
- Visually inspect all wiring to second O2 sensor for loose, open or short connections
- Use a wiggle test to determine where the voltage drops out
- Visually check for exhaust leaks or air inlet leaks
- Using an OBD2 scanner, check whether sensor 2 of bank 1 is switching properly.