Most likely the cat is bad. Unless the is an air leak in front of the cat in the exhaust; it is very likely the misfires ended up damaging the cat....ouch.

Answered by Service Writer (expert)
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What is the harm in living with the light on? Aside from the environmental issues - which I am concerned about - is there additional harm to be done if I don't repair immediately?

Response from caddiac
2 questions asked

Poorer gas mileage, potential burned exhaust valves come to mind. depending what happens. May give a lean mixture that can cause piston damage...But straight forward this is only my specuation.

Answered by Service Writer (expert)
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So should I replace one or both catalytic converters? Since there is one in each header coming together at the muffler I am not sure which is bank 1.

Response from caddiac
2 questions asked

Usually it is the left side, but let me check tommorow.

MAke sure the o2 sensors are not damaged or loose, that here are no leaks between the converter and rear converter flange.

You can check the grounds for the VCM, other sensor grounds, make sure there are no other codes right now.

I would still expect the cat to be bad.

Answered by Service Writer (expert)
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I purchase a set of catalytic converters from a internet supply house I found through this site. A "shade tree" attempt to install the converters resulted in a split 15 mm socket.

So I payed a local muffler shop to do the job. They had to cut them off, but my internet part fiit perfect and the problem was solved.

Parts and labor, around $500 including a donation to get some professional advice on this site. I consider that a deal!

Response from caddiac
2 questions asked

Good Idea replacing both, it's better off in the long run. Glad it worked out for you. And thanks for the donation!

Answered by Service Writer (expert)
9,918 answers provided