So my car has been in the shop for the past two days getting MAC LT's and an X-pipe installed. As of right now the shop just called and said that the car was done but they can't get the engine light to go off. The O2 extensions and MIL's are installed but the light just won't go off. They are going to recheck the car and see if there are any loose wires but i don't think they will find anything. Any suggestions???? Could the MIL's just be bad???

 

Do yo have a hand held tuner?
If the MILS dont work the tuner will be able to do it

 

+1. Disconect the battery(if you havnt already done that).

 

get them to read you the code and tell us what it is.

 

+1 you need the code to know where to start.

 

unhook battery 1st, get the code 2nd, then a handheld if needed.

 

Sorry it's taken me so long to respond.........the light is still on. I don't know the exact code but they've check it three times and it's for sure the rear o2's. The battery has been disconnected several times and after the initial 20miles it instantly comes on. Are the MIL's just bad then? I know the handheld will fix the problem but I really don't want to spend another $300 lol. Should I try disconnecting the MIL's and then replug them in to see what happens???

 

i hope there not charging you their labor rate as they continue to fool with it. id personaly get the back if there done with the install and mess with it myself.

 

If you have longtube headers then its a problem with the front 02 sensors. I had MAC lts and offroad prochamber put on with the MIL eliminators and my check engine light wouldnt go away. I thought the same thing and switched the MILS around and all kinds of stuff. I finally got the codes and looked them up to find out its because of the front 02 sensors not warming up fast enough because now they are further back (something along those lines) I got a tuner from americanmuscle and told them i had longtubes and they are able to fix the parameters in the computer to lengthen the warm up time. after that, no problems. the tuner also helps everything work more effecient as well. I will try and find my posts from when i had the same problem and post the links for your viewing pleasure.

 

https://mustangforums.com/forum/4-6-...odes-help.html

here you go.