The seal on the lens on these headlights separates from the housing and the heat from the lights causes moisture to be drawn in as the air inside heats and cools. The LED circuit board sits in the bottom of the housing and will corrode, leaving the LED not working. The fix is achievable but involves removing the seal and cover and wiring a jumper across the corroded area of the circuit board. There is a Youtube video of the process.

This is a manufacturer defect due to a low-quality sealant being used. It affects safety. GM's response has been to raise the price of replacement headlights from $750 to $1250 each. Aftermarket lights are available for $450 a pair.

Ok it's me again, not only did my brake light go out, now my driver's side headlight LED and turn signal went out. Had noticed moisture in the lens for a while. Then the LED's started going out. I figured, crap now the headlights are going to go out. Sure enough, the day I had the headlight replaced, the tech told me there is moisture in the passenger side too. Crap another $900.00 and that is just for the part. Tried to get others on Facebook to tell me if they were having this problem and got so many responses. I figure if this many people that I know are having this problem this must be a BIG problem nationwide. Not just Yukon, Chevrolet, Cadillac, So many GM vehicles. I sat with my turn signal on to turn left and a car pulled out in front of me almost got hit head on. Got out of my Yukon and the LED's were out completely. The turn signal is part of the LED unit. So I called to order the headlight and the response from the parts guy was Wow are we selling a BUNCH of these headlights... So maybe GM doesn't want to pay to fix this issue when they can make big bucks selling the headlights!! So how long before both headlights go out maybe at night and I get hit head on. Whose fault will that be! Oh and BTW there is no aftermarket for factory installed HID headlights.