Iv been throwing a code for about 6 months now before i started throwing the code for my cat my mechanic changed my cat cuz i was getting back pressure cuz it was clogged. Due to this code i can not get my car inspected and my mechanic can not figure out the problem it keeps saying catalyst but he checked the cat with many test and the cat is fine barely has 5000 miles on it does any one else have this problem and maybe know how to fix it car only has 57000 miles on it

 

is it a p0420 code?

 

Is it an aftermarket cat (Magnaflow)?

 

If you put in an aftermarket catalytic, there is a good chance that the computer still sees it as a problem because they are VERY picky when it comes to cats. Nothing could be wrong with it, but it doesn't meet the stringent parameters set in the PCM.

You could get the P0420 code tuned out of the PCM, or maybe put a defouler in place of the rear o2.

 

this X2 ^

 

Im not sure which cat my mechanic put it i will have to ask and get back to you guys thank u all

 

FYI - I moved this thread out of the "MCF Problems and Issues" as this is not a problem with the forum, it' car problem. It's now in Monte Carlo Repair Help.

Also, I removed the Info prefix from the subject. This is not providing members with info.