You're under warranty.

 

^+1

Also, never really heard of speed sensors going bad on an S197. But failing stepper motors are a common issue. Symptoms (from what you've described) seem to be pretty similar to a bad stepper motor as well.

 

Pretty sure that if either of those sensors fail it will turn your ABS light on and give you a code through a ABS code reader. It does in my Lincoln anyways. Not 100% sure but I think all the sensors go through your ABS module.

 

It's on the transmission and it's not hard to get to, but yours is a 2013, so just take it to the dealer.

It could be the actual gauge cluster that's going bad.

 

lol... This was 2 years ago! cooter05 decided to needlessly revive this ancient thread.

This was on my 2008 GT and I never had to do anything as the issue resolved itself.

I traded the '08 and my new '13 is flawless so far :-)