O2 Sensors

[LolaKink]

The check engine light is on in my 2007 Aveo. I went to Advance Auto Parts and they put it on the computer. The codes that it spit out are saying that I have a misfire in cylinder 2 and cylinder 3 also random misfires, it also gave the code for both the upflow o2 sensor and the downflow o2 sensor. According to them they are saying it could be the spark plugs causing the misfires and the misfires causing the o2 sensors. Or it could be the o2 sensors causing the misfires. I am not sure which and am quite confused. Anyone else have this issue?

[avguy]

The first question is how long has it been running bad and/or with the CEL, and how many miles are on this Aveo? What are the specific O2 sensor codes? O2 and cat codes usually don't start showing up unless the misfire has been going on for a while, so I'm assuming it's been running this way for a while. The first suspect for misfire is spark plugs and wires, and that's what's normally done first. But with specific cylinder misfire codes the coil is also a possibility. Also check to see if there is oil in the plug wells, which is caused by a leaking valve cover gasket.

[LolaKink]

It has been running bad for since Sunday, so as of today it has been 4 days. It has about 103k miles on it. and as for the specific code I am not sure exactly, the papers that I got with the codes written down on it got left at a friend's house when I went to talk to him about the issue. I have been told to change the spark plugs first and see if that fixes it, I have also been told to check the ignition coils and swap them and see if the misfire changes from the ones that it is misfiring on to the one it got swapped with as a way of kind of diagnosing the issue further. Going to get spark plugs later today and try that first.