Ok so I did a megan racing highflow cat and cat back exhuast install last night. The damn o2 sensor was a pain. After wrenching heating and spraying it finaly came out after about 30 minutes. Of corse it was striped so rethreaded it. There was 2 places to place the o2 One in the cat and one a little further towards the rear. I placed it in the further to the year location since I figured there was going to be more flow. I took the car out beat it for about 15 minutes or so pulling and driving normal and no check engine light. I started it this morning drove normal for about 10 minutes then did a pull and bam the check engine light is on. I called mitsu and they want 400 for a new o2 sensor . Should move the o2 sensor to the cat? Any suggestion on what I should try before I order a new 02 sensor?
This is a evo 9 by the way. Thanks for any help in advance guys

 

Have you pulled the code? Go to Checker / Autozone and borrow their code reader for free (not the dealership as they will charge you) and pull the code. It will probably be the P0420 which is cat inefficiency. This is typical with a high flow cat and there are lots of threads on how to fix it if it is such as spacing the O2 sensor out with spark plug anti-fowlers.

Good luck.

 

search 02 mechanical fix

no need to move to catback

 

do a hard FAULT RESET first..if the light comes back on...then for sure your gonna need the o2 Fix..very simple i have that on my cat delete. and no more light

 

Disconnect the battery for 5 min .. and reconnect it, this way the ECU resets it self .. and see the results .

 

yea, it is really simple i did thi on my 350Z

 

thanks, you guys rock. I will try all this and let you know what happens. I went to shmucks after I heard all this today and used there error reader (what ever its called) for free. Yes it was the dreaded 0420. I deleted the errors and the light went out. So we will see what happens. After about 10 miles still no light but I am sure it will come back on = P.