Finally!!! engine light comes on
 

Been waiting 3-4 months on it. Car been running fine but never seemed to be running perfect at wot and gas miles have been sub 16 till this week when they went to 12-13mpg over last 2 tanks. Code p0151 b2s1 kow voltage, one of the wideband sensors. Goes to shop on Monday to get fixed. And hopefully be running like it did when i first got it. Like a bat outta hell.
Question I have though is Ford won't give me any problems fixing it even though the car is tuned will they? Wouldn't think an o2 sensor going bad would be caused by a tune and should be covered under warranty. Car has 21k on it.

They shouldn't give you any issues. An 02 sensor failure is independent of a tune. It's not like you modified your exahust (well the catalytic area anyway) that they could point the finger at it.

Don't let them intimidate you, IF they try.

I didn't think they should. But thanks for the reassurance guys. And Rick u def know they won't intimidate me. I work at a dealer and used to write service so they will def be fixing it. Plus I used to work with the advisor that I deal with where I take her. So should be good. Also he won't let them download anything to the ecu bc he knows its tuned. Plus I'm putting a sign in the car.

Then you're set!

o2 sensors rarely fail, especially on such a new car. Hopefully it is just that, a bad o2.

I don't think it's an out right problem of the o2 sensors failing but rather there seems to be some that are too slow in responding to ecm. From what I've gathered from these forums and others is that the ecm in the 11-13 stangs are very sensitive to any fluctuations of data imput from the various sensors, particularly the 02 sensors. If the O2 sensors are even a few milli seconds slow in responding to the ecm it's enough to throw a CEL. The tricky part is if you test the O2 sensors independently they will test out ok. This is what was happening in my 11 GT(CEL came on 3 separate times). The techs were stumped. I gathered info from some of the forum threads and presented it to the service manager. They swapped out the O2 sensors. No more CEL.

Go figure. Light went off earlier and ain't been on since. Oh well. At least I didn't clear the code.

TSB 11-7-7 States that an aftermarket PCM calibration - non factory modification or aftermarket components on a 2011-13 mustang can void the powertrain warranty

Can =\= will. They must show cause.