Can an Oxygen Sensor Fail?

Most oxygen sensors do not quickly fail, rather they will slowly degrade in performance until they finally send a false reading to the ECU, thereafter causing the engine to run too rich or too lean, thereby setting off an engine light.

It is possible for a sensor to quickly go bad. If so, it is usually due to contamination of some sort, such as exposure to silicones, antifreeze, leaded fuels, etc. Alternatively, some sensors are ruined as a side effect of another engine problem. Since sensors fail so rarely, it is best to check for other engine problems prior to replacing your o2 sensors.