Running Lean

I just got the Check Engine light on my 2012 Tacoma. I took it to Toyota and they said the error is that it is running lean and should be covered. The only problem is that I installed Long Tube Headers and the O2 sim which seemed to work for 8 months, until last night. I imagine it won't be covered by Toyota, any ideas as to why it would randomly throw the CEL?

 

Afr sensor bad?

 

Not sure why it would just start sowing a code but you need to get a controller, the computer can't compensate enough for mods, I just put on the MAF cal from URD trucks runs and tows much better, I was running lean and had a high rpm lean out and just a touch rich in open loop...

I wasn't getting a code but headers will lean it out more than a cat back...

 

Check to make sure you don't have an exhaust leak, between flanges of the headers to Y-pipe.

 

I wouldn't automatically assume it is the headers. Check for an exhaust leak, as mentioned, and also check for an intake leak, both can lead to a lean code.

 

i checked for leaks and I didn't see any. Miraculously it the check engine light just turned off after I came out from work today. I have no idea what happened but thank you all for the responses!

My next mod is a y-pipe and then urd cai but now I will look into the MAF Cal as well