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Hello guys. I come from Taiwan.
My car is 02 Ferio (7th gen civic)
I have a bluetooth adapter connected to my ECU and monitor by android software, Torque.
I just replaced my 1st O2 sensor due to remaining in high voltsge with fault code.
Now I am wondering about my 2nd O2 sensor voltage (stay in 0.8). Should it be zero or close to zero if the oil supplying parameter normal (optimized)?
Refer to the snapshoot.
Thx.

 
Rep Power: 518

Rear O2 sensor voltage should not mirror the front after the catalytic converter is warmed up and operating, under many conditions. The rear sensor is used by the PCM for measuring Oxygen storage capacity (efficiency) of the catalytic converter, so it will read a much more steady and stable voltage at certain times, but not always. It may read steady high, then steady low, as the converter stores and releases Oxygen.
It WILL vary in many conditions. Difficult to explain here.

If rear sensor voltage follows the front sensor too closely, the PCM may judge the cat to be deteriorated (lost efficiency) and set the code P0420.



Watch what your rear O2 voltage does under all conditions, and assume that whatever you are seeing is normal UNLESS the car is setting a P0420 cat code (USA OBD2, not sure about other markets).

Better yet just ignore the rear sensor completely unless the PCM sets a cat code.

http://www.fordscorpio.co.uk/obd2scan4.htm