Have a 2011 MKZ hybrid (100k miles) and have been noticing a drop in mileage of 15% since the starter battery was replaced 12/18. I mentioned this to the dealer who replaced spark plugs and filters saying this would fix the problem. Not! Mileage continued to fall from 40+ to 35. It was not until websites like this one and talking to a mechanic friend that I learned about a Ford Tech Service Bulletin (20-2142) that addresses this exact problem of the bcem and pcm modules reprogramming. Took the car back in and asked the dealer to check this TSB and surprise! the problem was fixed. The car runs in EV mode again....almost like new.i Ford was definitely negligent in not reprogramming those modules that was clearly stated in their own TSB.. Love the car, but shame on Ford for not being proactive and needing an owner to uncover the fix for the problem!
