Ok so i bought a turbo back exhaust with a test pipe last summer and got my evo 9 tuned. Then i had to get it inspected last april so my friend who did it said buy a spark plug anti fouler i did and installed it for the o2 sensor. the light went away got my stickers everything was cool. but now sometimes when it rains alot the light comes back on. My evo runs fine, knock on wood, so i figure its just the sensor still throwing the code. The light will go off after a day or two. Anyone have the same problem? or should i really get this looked at?

 

you can disable the rear o2 code in the peripheries or with the resistor mod

There are writeups on both, just search

 

Just to be sure, check what codes the ECU is throwing. If it's a P0420, it's the cat.

 

ok how can i check myself not to sound like a newb or do i have to take to a mechanic? it will prob be off next time i start my car happend like 4 times since april.

 

just buy cheap obd2 reader ,

 

yeah i should invest into one of them anyways. how much they run?

 

I picked one up from Pepboys for like 30 bucks. All it does is give you the code number which you can look up with the software that is included with it or via the internet.

I would try to link you one from their site but it is god awful. I am sure you can find one at any autocare place such as Autozone, Pepboys, hell.. maybe even Walmart.

 

If you have a laptop use the scanOBDII for free. If you have access to a tactrix cable then you pull the code easy peasy and clear it. If not you local automotive chain should be able to pull the code.