I have a 2002 4runner. The exhaust flange rusted through and on my way to the repair shop, as expected, the check engine and VCS lights came on due to the exhaust leak. I got the exhaust fixed and reset the lights with the positive battery cable disconnect. The lights went off but came back on. I just replaced both O2 sensors last month. Could an O2 sensor go bad that quick? I only drove 12 miles with the exhaust leak. Thanks in advance!
Check Engine Light question
- Thread starter Ray H
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The PO did a hack job on the exhaust on mine and I had the same issue. I replaced both O2 sensors and it did not fix the problem. Ended up being that the CATS were bad. I bought new cats muffler and tail pipe with all the gaskets and hangars from amazon and it fixed the problem. Might need to have it looked at from midas or someone that does a free check and see if they are bad. That or try to Sea foam the engine and it might clean out the carbon build up in the exhaust and fix it, but probably not. I live in Hawaii and got everything from manifold back shipped to my door for under 900 and it took about 4 hours to do because of rusted bolts and the hack job from the PO to get the loud muffler installed.
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TheDurk
Elite Member
Since the OP's CEL came back on immediately, it's unlikely to be the cats. The cat efficiency test takes a minimum two drive cycles to complete and usually takes the better part of a tank of gas. It will probably turn out to be an o2 sensor code, but OP really needs to pull the exact code. The sensor is unlikely to go bad, in that short a time, but sometimes they are bad right out of the box. It could also be a connection problem. Did you use Toyota or OEM Denso sensors? Anything else is a mistake.
If the codes came back immediately, it's likely a circuit issue. As stated above, cat and O2 sensor monitors take a while to run. Circuit checks don't, and will set faster.
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