oxygen sensor code P0136

[akkhandelwal]

I have 98 ford windstar with 3.0 engine

I have check engine light on with code P0136, which means Bank1, sensor 2 malfunction.

How to find which one is this out of the 4 sensors installed on this van

Thanks

[wiswind]

P0136 is the downstream sensor for bank #1....Circuit malfunction. I would check the wiring....make sure that it is not touching something. There is another code for the heater malfunction for this sensor.....so it is the sensor circuit.....not the heater circuit.

Downstream is AFTER the catalytic converter.
Bank #1 is the back of the engine.
Bank #2 is the Front of the engine.

The downstream oxygen sensors monitor the catalytic converters to make sure that they are working.
The upstream oxygen sensors monitor the exhaust....and are used by the computer to control engine functions.....like air / fuel mixture.

[wiswind]

I want to add another note....I have a '96 3.8L.
The factory converter that is connected to the rear bank of cylinders.....is the rear most converter under the car. The downstream oxygen sensor is mounted into the back of the converter. When I changed my catalytic converters.....this sensor broke out of the converter with very little force. I had the converters off the car....and was able to apply only a turning pressure.....and the threaded ring broke out of the thin metal of the converter.
If I had not been replacing the converter anyhow, this would have been a problem. So please be very careful.....and think twice about removing this sensor if you do not absolutely have to.

[akkhandelwal]

Thanks for the tips.

If this is the one after the catalytic converter, how do I know whether the converter is defective or the oxygen sensor.

It happened with me earlier, I was getting code for EGR malfunction and was about to get the EGR valve replaced. But it was the EGR sensor which was defective not the valve.

[wiswind]

If the one sensor is not mounted into the back of the converter it's self......then you could switch the sensors from side to side. If the failure code changes to the other bank......then you have a bad sensor. If the code stays the same.....then you have a bad converter or wiring to the sensor. I would then verify the wiring for the sensor.....as the converters are expensive.