We recently purchased a '02 Lancer OZ and the check engine light came on. The only trouble code that the computer reports is:
P0421 - Warm Up Catalyst Efficiency Below Threshold (Bank 1).
The car is no longer under the bumper to bumper warranty (has 37k miles), so I want to avoid the dealer if possible. Does anybody have any idea as to what the problem could be? The car runs smooth, so there is nothing visibly wrong with the way it runs. Thanks in advance for any insight to my problem.