| Failure |
Causes |
Effects |
| Oxygen sensor contamination by coolant antifreeze |
Wom or damaged engine gaskets or components which cause coolant leakages in the exhaust. Ethylene glycol(antifreeze) of coolant contaminate the oxygen sensor.
|
Slower or miss sensor signal output. Head? shows grey scaling over whitened metal |
| Oxygen sensor contamination by silicone. |
Silicone particulates in fuel or in the air/fuel mixture which contaminate the oxygen sensor. |
Slower or miss sensor signal output.Sensor shows a fully whitened head. |
| Oxygen sensor contamination by lead |
Bad quality fuel may still contain lead. Lead in the fuel mixture fast contaminate the oxygen sensor. |
Slower or miss sensor signal output Sensor head shows red-brownish metal. |
| Oxygen sensor contamination by hydrocabon depots |
Faulty idle air control electrovalves or stepper motors£¬ faulty pressure sensors or other engine management components cause a too rich mixture£¬ which contaminates the oxygen sensor. |
Slower or miss sensor signal output. Sensor head shows black hydrocarbon depots. |
| Oxygen sensor contamination by oil fumes |
Wom out piston rings£¬ wom or damaged engine gaskets or components which cause oil blow-by or leakages in the exhaust. Oil fumes contaminate the oxygen sensor. |
Slower or miss sensor signal output. Sensor head shows greasy oil depots. |
| Oxygen sensor signals modified by bad electrical connection |
Moisture or dirt into the sensor connector£¬ as well as poor or incorrect wiring connection of "universal" sensors£¬ loss of grounding of 3-wire sensors due to corrosion or dirt on threading£¬ etc. cause electrical problems which affect both the sensor and eventually the engine electronic control unit. |
The sensor works with shifted characteristic£¬ or incorrect signal levels£¬ or gives no signal output. Further damages may result to the sensor itself or even to the vehicle electronic control unit. |
| Overheated oxygen sensor |
Defective ignition module£¬ incorrect ignition timing£¬ excessive spark advance£¬ cause pre-ignition and engine knocking£¬ with power loss. The exhaust gas reaches a too high emperature and overheats the sensor. |
The sensor is damaged and gives no more signal output. Overheat effects are visible over the sensor head. |
| Fracture of oxygen sensor ceramic substrate |
Cold water upon a very hot oxygen sensor may cause a sudden cooling of the sensor£¬ which is transmitted to the inner ceramic substrate and causes its fracture. |
The sensor is damaged and gives no more signal output. Broken inside ceramic and other effects over the sensor head can be noticed.?? |
| Oxygen sensor damaged by extemal cause |
Road debris or stones which hit an oxygen sensor fitted below the vehicle£¬ or any other hard mechanical shock£¬ damage the sensor case or cable causing short or interruption of the wiring hamess. |
The sensor is damaged and gives no more the wiring hamess. signal output. The effects over the sensor case and/or the electrical hamess can be noticed. |
