Oxygen Sensors
Oxygen Sensors
Section titled “Oxygen Sensors”The M54 uses 4 oxygen sensors (lambda sensors) to monitor air/fuel ratio and catalytic converter efficiency.
Sensor Locations
Section titled “Sensor Locations”- Bank 1, Sensor 1: Pre-cat (before catalytic converter)
- Bank 1, Sensor 2: Post-cat (after catalytic converter)
- Bank 2, Sensor 1: Pre-cat
- Bank 2, Sensor 2: Post-cat
Symptoms of Failure
Section titled “Symptoms of Failure”- Check engine light
- Poor fuel economy
- Rich or lean running
- Failed emissions test
Replacement
Section titled “Replacement”- Pre-cat sensors: Replace every 100,000 miles
- Post-cat sensors: Longer lasting, replace as needed
- Use OEM Bosch sensors for best compatibility with DME