"Check Engine Soon" after LT install...

Discussion in 'SN95 4.6L Mustang Tech' started by KwikZilver, May 11, 2005.

  1. Had my BBK LT headers installed last Wednesday, and everything was fine. Ran great but Saturday night leaving my friends house the "Check Engine Soon" light came on. Someone on another message board said I need MIL Eliminators...

    What does everyone here think? I did need to use the O2 extentions on the front O2's but the rear ones reached fine. Any idea's?

    Thanks in advance...

    Forgot to mention that I installed the BBK Catted X-Pipe at the same time as the headers.
  2. ...

    Get the code pulled and we can tell you what the problem is ...did you reset the computer after the install? since you have catted x pipe you shouldnt need mil elim's .....
  3. I have heard that in some cases after market cats flow to much air and do throw codes as a result. You may need mil elim's..but as other people said just get the car checked see what code it's throwing
  4. it'll be one of two things usually after a lt install. either the o2's, or the egr will throw the code if something is not done right, or you didn't get the mils & need them
  5. Thanks, guys.

    I'll go get the code scanned this Saturday and get back to ya.
  6. yea im having the same problem, only my mil lite come on and off like every four days. i pulled the codes and it came out P0153 low circuit voltage sens.1 bank 1. or some times ill get P0133 low circuit voltage sens1 bank 2. or combination of the two. i just replaced both sensors with bosch unitslike 6 months ago and its still doing it.

    ps i didnt use extenders the sensors i bought came with a 13" harness.
  8. The reason LT's are not emissions legal is because they put the cats too far from the engine and they don't light off properly. The computer is looking at both O2 sensors (per bank) and comparing them. If the computer does not sense the correct values from the O2's, which it won't because the cats are not lit in time, then it will throw the engine light every time. The mils send the correct values to the computer and fool it so no light comes on.
  9. you could also tune the o2 sensors out, I have a O/R x-pipe with my LTs so of course I threw a code, gonna try o2 simulators for it.
  10. I had mine come on after my LT's were installed too, and I just got done putting homemade MIL eliminators on. It was easier than hell to do, and it cost me a grand total of $9.54 for the parts from Radio Shack. I do have another question regarding this: when your "check engine light" comes on, does that effect fuel economy at all? The reason I ask is because the first two days after the LT install I was getting great mileage but after it came on my mileage went down the pooper. Thoughts?
  11. The 02 sensors need to be heated to work and send the signal fast enough. When you use extensions it takes longer to send the signal, thats why it says "low circuit voltage." I had this off and on for awhile, then it just stopping coming on.