My 2002 MC spit out a P0136 fault code which pertains to the O2 sensor (bank 1 sensor 2). Is that the post cat O2 sensor and should I assume this to be the cause for the fault? The car has 90k mi. Any thoughts are appreciated.

 

Yes this is the sensor after the cat. Make sure you get an OEM as they work the best IMO.

 

Check the wiring on it before you replace it. They are known to rub on the shielding and throw codes. If you can check the flexible joint in the exhaust header check that too. Apparently I had a small hole at the joint (couldn't even hear it leaking) that kept causing the error code. Didn't know that was the cause until the joint broke, and I had it fixed.

Nik

 

Thanks for the input. The SES light comes on intermittently. I'll check the wiring, but I suspect the O2 sensor is getting flaky after 90k mi. The shop manual suggests 100k change out. The OEM O2 sensor runs $285. per unit.