My SES light keeps coming on and giving me a code (p0420 I think, but don't quote me) that says that I have a catalytic converter deficiency. Someone told me that 9 times out of 10 that its the O2 sensor. My car is a '96 and it only 59k on it. I can't see how it would be the cat. I just had to replace the heated sensor in bank 1 about a month ago. Cascading type problem? Moved on to the next O2 sensor? What is your opinion?

Thanks,
Jason

 

Change the O2. The cats on these cars are pretty good, I'll bet yours is ok. Does the car smell like rotten eggs at all? That is a telltale sign of a clogged cat.

 

ive changed cats on cars with 20k miles. If you run a car 100 miles with a misfire the you probibly junked the cat, it may be able to bake the debris off eventually, or mabye not. If thats the code I'm thinking it is it means that your post cat 02 is showing lower o2 readings to your pre-cat o2, so, any of the 3 could be the problem. you can use an inferred thermomater to check the cat, but you need a DSO to check the O2s. If you have had any problems that would cause the cat to gunk up its probibly the o2s.

 

I just changed the plugs on the car about 2k ago and the old plugs were only in for about 6k. I had an exhaust leak coming from the exhaust manifold gasket so I changed the plugs at the same time. I haven't had any problems with misfires. No rotten egg smell either. I'll try to change the o2s and see if that fixes it. Thanks for your help.

Jason