Hey,

I have browsed these forms for awhile now but really haven't ever posted. I'm having a annoying problem. I own a 04 5AT TL and have a K&N CAI & a custom exhaust system which is straight piped back from the CAT.

I'm getting a CEL for Catalyst System Efficiency Below Threshold.

My o2 sensor has been replaced and I've reset the code 5 times now. The dealer told me its because of my intake/exhaust. I really don't want to remove either. Is there anything I can do to get rid of this code? Any help would be greatly appreciated.

 

the dealer is full of shit...its probably a bad cat...and btw, which sensors did you change? the primarys? or secondary? the latter are the o2's and those are the ones that check for the cat if its working

 

Honestly, I don't know which sensors were changed. I brought my car in for service and they diagnosed the check engine light as a bad o2 sensor and swapped out the sensor. The check engine light came back on within a week if I remember correctly.