Q: Check engine light came on, stayed on for a month, then went off.

asked by on August 06, 2017

My cars check engine light came on 5 days after I bought it while I was driving. The VSC TRAC/OFF, and the slippery when wet lights also came on at the same time. I read the codes and it came back P0430, the catalyst system. I cleared the codes and they came back on a few days later, same thing. I've had the car for almost a month now and when I turned it on today the lights didn't come on. I tested for codes after the lights went out to see if it would read anything and the code reader found codes P0430 and P0420 while the lights had gone off. Could this just be a bad sensor. Or do you thinks it's an exhaust leak or a bad cat?

My car has 160000 miles.
My car has an automatic transmission.

Hi there. In most cases, the P0420 code means that either the upstream or downstream oxygen sensor in the catalytic converter is not working. The other code listed tends to be caused by issues with the catalytic converter being damaged. Based simply on the codes, I would wager that your catalytic converter is damaged or worn out and needs to be replaced. However, any mechanic that will make a diagnosis simply by the codes listed is not a good mechanic. So, I would recommend having a professional mechanic complete an onsite inspection to determine what is causing these issues and recommend the right repairs.

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