Since the oxygen sensor is in the exhaust stream, it can become contaminated. Common sources of contamination include an excessively rich fuel mixture condition or oil blow-by in an older engine and engine coolant being burnt in the combustion chamber as a result of on engine gasket leak.
It is also exposed to extremely high temperatures, and like any component can wear over time. These can all affect the oxygen sensor’s response characteristics, resulting in an extended response time or a shift in the sensor voltage curve and in the long run reduced sensor performance.
What to look out for in a failing 02 Sensor:
- Check engine light
- Poor fuel economy
- Rough engine idle or misfiring
- Sluggish engine performance
Common Fault Codes:
- P0135: Oxygen sensor in front of the catalytic converter 1, heating circuit/open
- P0175: System too rich (bank 2)
- P0713: Fuel trim malfunction (bank 2)
- P0162: 02 Sensor Circuit malfunction (bank 2, sensor 3)