My check engine light was on, went to Autozone, they did the test, said it was my Cat converter and to change the spark plugs. I did that, unplugged my battery to reset my system, and check engine light came BACK on.My father and stepdad both think it‘s probably the o2 sensor.What is that, and is it expensive to have done?
many people make the mistake of going to autozone and having their codes read.autozone is in the parts selling buissness not the auto repair buissness.maybe theres more to the story than you wrote in your question,,,,but them telling you to change plugs was wrongyou have already spent money that may not have been needed now your giong to spendanother 100 on a o2 senser on a guess.sorry but todays cars need diagnostics run on them by a qualified tech with modern equipment,,,parts are to expensive just to take a guess at whats wrong(unless you want to start a relationship with the guy at autozone).its hard to believe that a 04 corolla needs a cat,and your dad could be right but unless u have somebody that knows what they are doing look at this issue.u could be spending lots of money and your car will still have a ses light on .
If you have a code for the catalytic converter then that is what you are going to need. They led you very wrong with the spark plugs. Oxygen sensors can affect the performance of the converter but if that were the case then you would have codes for those too. You may still be under warranty on the converter - typically they have an 8 year / 80,000 mile warranty. Good luck.
