I have an '04 with a few mods,(K&N CAI, Dal exhaust, and long headers). Recently i bought the Superchips Cortex Tuner and uploaded the 87 octane tune, soon after i got the P0420 code for the Catalytic effiecency Bank 1. i only have 68,000 miles on the truck so i wold be suprised if the CATS were bad. Also ive seen pics of the cat converter and it looks nothing like what i have, i have 2 seperate cats(i think).
Would the CATS go bad that fast and have to be replaced? If its the sensors, how do u know which one to replace?