02Lancer ES giving me a code p0421: catalyst below temp threshold bank

Search results all over the place seem to vary wildly as to the actualsolutionto the problem as well as the cause:
"Replace your cat"
"Replace O2 sensors"
"Dont do anything, its cold outside, itll go away"

I hate to throw parts at it without a sure diagnosis. Any help appreciated!

 

its the cat...

 

recall on that. call mitsu.

 

Ok, I did a recall service visit this week. The only things on an '02 are PCM reflash and fan control switch. The PCM reflash might solve the intermittent P0421. I bought an OBD reader and cleared the code. So far after a week it's not coming back.

 

the reflash will not cure the failed cat. It is to prevent the cat from failing.
If you have under 100K on the car, it should have been replaced as part of the recall. If you have over that, its no longer covered.

 

what should he do if is over 100000 miles ? replace the cat ?

 

Cats are covered under fedreal warrany 8 years 80k miles. If your over 100k looks like your paying for it out of pocket.