# Changing the O2 sensor, should I replace the Cat at the same time?



## Edog1382 (Aug 9, 2006)

So the check engine light came on and I got a Code P0136.. "Bad rear O2 sensor"... My question is, i noticed the car smells like rotten eggs when I'm parked on a slight incline and idling. I was wondering if my O2 sensor got blown because I have a bad Cat... I just ordered a new O2 sensor, is it worth spending the time and money to throw on a new cat. Could a bad cat cause a O2 sensor to be blown? Any bright ideas?


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## Jeff (Oct 17, 2002)

I'm wondering if a bad cat could possibly give the o2 sensor bad readings causing it to malfunction or lose life-span.

Regardless, a rotten egg smell does mean you need a new cat. Replace it, reset your ecu and see if the code comes back.


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## Edog1382 (Aug 9, 2006)

So I have been researching cats. Do I have to weld one on. or are they just bolt on. I never realized they were that expensive!! 100-300 bucks! holy crap! Id like to be able to do it myself if possible. I got the o2 sensor, but im going to wait till i replace the cat before i install. thanks jeff!


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