Well i installed a magnaflow high flow cat a couple months ago and i failed my emissions because of the cat..I erased the CEL that popped up a day or two after installing but showed back up..I was doing a little research and to "possibly" fix this rather than replacing the cat is to pour lacquar thinner into the gas tank..with it half full of gas and run for about 150 miles and the code will turn off? any ideas or anyone dealt with this problem..thanks

dont think thats why cause mine passed with the same type of cat it could be something else

doesn't sound like a good idea, but i would like to hear the reasoning...probably would be hard on all the injector o-rings.

the cat monitor uses the o2 sensors to monitor the cat efficiency. If the front and rear switching or cross counts are the similiar it knows the cat isn oxidizing the hydrocarbons. Putting anything in the fuel tank isn't going to change the switching times on one 02 and not the other.

What code is setting? Post the code and address it the right way.

If its a p0420 low oxygen storing efficiency the cat probably has low cerium content; the element used in the cat that stores oxygen. Aftermarket cats have less cerium and thats why they are cheaper.