Common failure modes

Failure modes of oxygen sensors：

Oxygen sensor getting poisoned is a breakdown which is common and hard to deal with, especially when the leaded petrol used. Under this condition, even the new sensor can and only can run for several thousand miles.

Brown Top: Lead poisoned, if the situation is serious, a new sensor is required.

Normally, petrol and liquid lubricants will create Silicone Dioxide after get burned. And the rubber sealing ring emanates organosilicon gas when it has been mal-operated. An oxygen sensor would fail under these two cases. Therefore, we need to use the qualified fuel and lubricants.

When repairing, please install the rubber sealing ring in the right position. Also, no other liquids can be applied on the sensor except for manufacturer’s regulations.

White top: caused by the silicone poisoned, a new sensor is required.

If there is no sufficient burning within the engine combustion, sensor surface would be covered by carbons or the oil dirt and dusts would slip into the sensor. Once this happened, it would stop or stuck the air coming from outside to the inner of the sensor, then cause a fail on the signal precision. As a result, ECU will have a wrong air-fuel ratio feedback and fail to control effectively.

Carbon deposit: Fuel consumption increased emissions rise.

Signal wire broken

Cooling liquids poisoned

Contamination from outside oil dirts