I have a 96 Mustang V6 and i haev had it in and out of the shop with the check engine light not going off. After i get it back from the shop i ride about 6 miles and then it turns on again. Its not the vacuum but it was checked ata autozone and the scanner said it was something in the exhaust. Do u think it could be the o2 sensor ?????

 

did they give you a code #? well if its in the exhaust I am pretty sure youre o2 sensor is on its way of dead.

 

If it had to do with exhuast it's gotta be your O2.

 

While I agree that its most likely your 02 sensor, it doesnt mean that its gotta be it. You gotta consider that all a "code scanner" does is read the 02 sensor voltage and if its outta the accepted range it throws the light for it. Other things could be causing the 02 sensor to read actual rich/lean conditions. Also, things like the egr valve etc. could also be the culprit. If it takes a few minutes for the light to throw then its most likely not a vacuum leak - its something that is only being read by th CPU in closed loop - like emissions related components.

If your shop can't get the light off then you need a new shop my friend.

 

I had the same problem in my 96 V6 when i first purchased it and didnt think a whole lot of i, it was just annoying. I eventually replaced all O2 sensors and the light STILL was on! I learned later that it was the O2 sensors but the cpu still sends the signal to the gauge cluster for some reason until the cluster panel is reset. If you really want it off and want to save yourself the money of having a shop do it just pull out the cluster and plug it back in after youve replaced the O2 sensors, this might get you a tiny bit of gas milege as well as fix your little light problem. Good luck with it.