Bought my CPO 2017 GTI back in June with about 34k miles, it was an off lease car and super clean.
First 6 months were problem free, only thing I had to do was just an oil change. Dealer changed the DSG fluid, threw on OEM pirellis which are awful and basic things before they put it up for sale. I enjoyed the car a lot, but then started seeing a small coolant leak around September.
Didn't think much about it nor did I fill it as I wanted to watch the speed it leaked, which was very slow. I live in the NJ/NYC metro and don't drive too often except for when we visit my in-laws in Upstate NY, typically I save this time for installing mods and doing service.
So it's now got about 40k miles on it, I am still here up north and the car took forever to heat up one morning. Usually I get heat within a mile of driving, I drove about 5 miles and the oil temp was 160 and the coolant was only 158, which was super strange. But as I turned the car off and came back later to go somewhere, it was fine.
Finally I made an appointment and dropped it off at the local dealer here and just a call this morning, welp no surprise it's the Water Pump, they're replacing the thermostat as well. I told them about my sunroof creak and will apply a "modification" to fix the creak.
Said it should take about a day or two since they need to order parts. I'm not mad since it's a CPO but I never had a car with such an early failure in it's life, I don't feel that it's unreliable as any other car but to be honest, it's not like a completely brand new engine they just came out with.
Kinda amazes me that Germans cannot get cooling system reliability down like the Japanese (I had owned a E39 at one point).