I recently got a check engine light notification and after taking the car to the dealer was told it was a p0420 code, meaning there was a problem with the catalytic converter. They said we'll replace it for $900+ so I said no thanks. The tech guy said he would reset the ecu and the light would probably come back on after driving for 20+ miles. It's been over 2K miles now and no check engine light. I'm wondering if there was a small glitch and there really isn't a problem with the converter itself. I have no problem replacing it if it's defective, but see no need if there's nothing wrong. I'm averaging 25+/-mpg per tank with mostly highway driving if that's worth anything. Any insight would be greatly appreciated.
'98 EX with 88k miles.

 

No code, no worry. If it comes back on dael with it, if not don't worry about it.