i just recently put a passester header 2.5 to magnaflow high flow cat vibrent 12inch "bottle" style res and 2.5 to the magnaflow muffler after doing so it turned the check engine light on i scaned it and said rear o2 sensor slow to respond so i picked up one of those j bends put that in and the o2 sensor in that and cleared the code a day and a half later it came back on what can i do about that? and also should i get a tune? i have a ported and polished tb and aem cold air soon puting on a H.O intake mani
thanks in advanced
Dallas

get a hold of a live data scanner chech to see if that rear sensor is responding slowly that's usually when they are starting to fail. i wouldn't worry about a tune yet till you start really adding a higher volume of mods as your ecm can handle about 20%extra fueling as need be to that point.

if you put a aftermark cat on it will throw the code, ur only option is a new factory cat, or hpt

What code exactly did it throw? I'm thinking you got slow response for the primary sensor, which is not uncommon when doing a header.



FU Tuning

The O2 sensor position is farther away from the head those isn't getting heated up as quickly as it would in the stock location. I have the same code and I'm gonna change out the current 2 wire to a 4 wire heated o2 sensor and that should fix it.