O2 sensors or bad cat converter?

[SKM348]

Just bought a 2003 LX with 105k on it about a month ago. Got a check engine light random misfire code, previous owner put a new cat converter in, off of eBay. Check engine light is back with same code. Mechanic that diagnosed it sent a note on my behalf to ebay seller asking for a new cat. Seller said his cat is good, and that the protege is notorious for bad O2 sensors. Will only replace it if we send it back so they can check. Freight is $34, and I don't like this option. Am planning now to put in both sensors at ~$170 and see what happens. If code comes back I think I'll get a new cat (Walker brand) with 5 yr warranty from Rock Auto at appx $182 after rebate, which is a pretty good price from a reputable parts house. Btw, will also put in new plugs while I'm at it; they only have about 25k on them but it's so cheap that I can't not do it.

Any comments on my approach etc? Are cats and or sensors known to go bad around this mileage?

Car is great, I owned an 03 ES 5sp that I sold at 80k and it was bullet proof and I know this cars can reach 300k w/o issues.

Thanks for the help!

 

[agr99]

Whats the code?

 

[SKM348]

Whats the code?

Don't know right now- will have to get from mechanic and let u know.

 

[Keno1542]

A lot of people will diagnose a bad O2 sensor if the O2 code is thrown. But most of the time, that is just the sensor doing its job and telling you something else is wrong. Not saying that is the problem here, but I do know a lot of O2 sensors get replaced because of misdiagnosing.

 

[SKM348]

A lot of people will diagnose a bad O2 sensor if the O2 code is thrown. But most of the time, that is just the sensor doing its job and telling you something else is wrong. Not saying that is the problem here, but I do know a lot of O2 sensors get replaced because of misdiagnosing.

Thanks. Since we still have a CEL I don't mind replacing the sensors. We plan on keeping the car a long time so I'll at least eliminate them as suspects. If we still get CEL I'll get a better cat with better warranty. At this point I'll have new plugs, sensors and cat which I hope will correct the problems.