I drive a 99 Coupe LX and was wondering around what time/mileage do you guys recommend changing the catalytic convertor? And if you change it what else might be wise to change? I don't have any tell tale signs of anything wrong right now but was curious since I found a really good deal on a catalytic convertor and O2 sensor. Thanks in advance.

 

there isnt any time or mileage interval to changing your cat. when it goes you'll know and you will get a code.

 

Not for a long time, unless you got a lemon or you constantly run a bunch of injector cleaners and gas additives all the time, etc.

Just the other day at the dealer... Parts guy: "Very rarely do we ever see a cat. go bad."

If you are having a specific issue in a related area, then it may be the O2 sensor. Those will go out at some point.

 

...definitely not prevantative maintenance. It's not like spark plugs or an air filter. The cat either functions properly or doesn't, and the PCM will tell you when it doesn't. The V6 cats typically last anywhere from 150-200k miles (I've heard of a lot of failures), while the I4 ones seem to last a lot longer. Was this an OEM cat and O2 sensor or a knock off?