One problem related to frame rust has been reported for the 2012 GMC Yukon. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2012 GMC Yukon based on all problems reported for the 2012 Yukon.
I have been a long time buyer of gm products, I still have a 99 tahoe, 07 GMC savanna and an 02 GMC sierra hd 2500, recently purchased a 2012 Yukon xl denali used with 22,000 miles on it from old saybrook GMC in CT, clean as a whistle everything looked, went to wash it and spray underneath in the first week after I bought it and noticed underneath the frame wax all pealing and frame very rusted, along with many other things rusting . My 02 with 170,000 miles on it looks better then this. Also went on line and there are a lot of people complaining about the same thing. Im sure more would if they looked under there car. This has got to be a factory defect and they need to fix this problem. The dealer is telling me thats normal , I disagree seeing I have multiple cars/ Gmcs my wife has a 2012 passat we bought new and is spotless underneath, and we have done nothing to the car.