Engine O2 (oxygen) sensor.
monitors the amount of unburned oxygen in exhaust gases to calculate the air-fuel ratio, allowing the ECU to optimize fuel efficiency and emissions. Positioned in the exhaust system, they typically trigger a check engine light, poor fuel economy, and rough idle when failing. (typically P0130–P0167)
A broken engine O2 (oxygen) sensor causes the check engine light to turn on, poor fuel economy, rough idle, and increased emissions, often resulting in failed emission tests. It can lead to severe engine performance issues like stalling or stalling and may damage the catalytic converter if not replaced.