One problem related to differential unit has been reported for the 2012 Subaru Legacy. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2012 Subaru Legacy based on all problems reported for the 2012 Legacy.
Transmission shakes or rumbles between gears while accelerating. Occasionally car will completely lose power and stall. This started happening with mileage at about 97,000 in February of 2018. Subaru dealer in danbury, CT said it was a propeller shaft and rear differential problem. Then brought car to Subaru dealer in brewster, NY who recommended transmission replacement. Service bulletins online describe the exact problem happening on the Legacy 3. 6 transmission. Car now has 121,000 miles on it. Car functions, but vibration between gears continues. Also occasionally completely loses power momentarily - very dangerous. Dealers say blue book value of my car is less than cost of a replacement transmission. Contacted Subaru of America who offered me a $100 goodwill parts & service coupon.