Three problems related to transmission noise have been reported for the 2012 Ford Mustang. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2012 Ford Mustang based on all problems reported for the 2012 Mustang.
I took my 2012 Ford Mustang (62,000 miles) to a Ford dealer to have the oil changed. They talked me into a transmission fluid change, because it would "extend the life of my vehicle". When I picked it up, it was not running right. The wrench light came on and the transmission was making a very loud noise. I had to have it towed back to the dealer. They replaced some sensors and sent me on my way. I made it home but the car wouldn't start the next morning. To make a long story short, after them attempting to fix it 3 times and it still not being fixed, they finally replaced the power train control module. I picked up the car and it still making a loud noise changing from 1st to 2nd gear. I see that there has been a recall on some 2012 Mustangs for a power train control module. I was never notified of this recall.
Was turning left at approximately 35 mph to get onto hwy on ramp. Had clutch in on manual transmission and stick in "out of gear" position during turn in anticipation of dropping to lower gear to gain acceleration. Was unable to put stick into 5th gear after three attempts - seemed "locked out" of gear. No grinding noises like the clutch wasn't in; just like the gear slot didn't exist. I released the clutch and pushed in back in and was finally able to get the transmission into 5th gear.
Shortly after purchasing 2012 gt Mustang (6 speed manual) we starting experiencing transmission issues. 2nd gear had a rattling noise and 5th gear had a significant vibration. County Ford had the vehicle for two weeks performing repairs. They replaced 2nd & 5th gear and I have a long detailed list of repairs on the invoice. I've only driven the car a few times since getting the car back. It's different but I'm not sure its repaired. I feel vibrations in 3rd & 4th gears now and 2nd sometimes grinds when you put it in gear.