My Dads last 2 new ford trucks (2012 and a 2013 both with 6.7 Powerstrokes)had to be towed to the dealer with under 20k miles. The 2012 had 11k miles when it flat out quit due to a NOX sensor (best I can remember) in the tail pipe going bad. It displayed a "please pull over safely" message on the DIC and Immediately quit in the middle of the road without giving enough time to pull over, we're lucky that it happened on a back road and not on the interstate or trying to merge somewhere. Constant emissions issues and reduced power. The 2012 had the rear pinion seal replaced 3 times in the 20k miles we kept it for. Traded it for the 2013 and had a lot of trouble with it as well, it was kept for 80k miles and was a headache the entire time we owned it, it would have reduced power constantly... take it in and they'd tell us it had a vacuum leak and that they had it fixed. The issues would resume before we could make the 30 mile drive home from the dealership. The 13 also developed a bad oil leak at the turbo, I believe they replaced the turbo under warranty. The 2015 and up Fords use a different turbo and are supposed to be more reliable, but I have no experience with the newer 6.7 Powerstrokes.
We finally got fed up with the constant run around at the Ford dealer and he traded it for a 2016 LML Duramax. Over 3 years later and 52k miles (3,700 engine hours) we haven't had any issues with it other than a couple of recalls. He says it's his favorite truck he's ever had.
In December of 2018 I bought a 2017 L5P Duramax and it has been trouble free as well. 21k miles and about 1,000 engine hours on it so far. I bought it with 10k miles.
I hear that the new Powerstrokes with the 10 speeds are pretty good trucks but I'm not real hot on Ford after the last 2 Ford trucks we had. Bottom line, if either of us were in the market for a new truck I think we'd both look at GM first. I test drove a Dodge before I bought my Duramax... I wanted to like it but just didn't. My Dad had an 03 Dodge 2500 with the Cummins (bought new), it was powerful but did not hold up well. The newer Dodges are are said to be better in the reliability department.
All of our trucks have been emissions compliant and I think that was the majority of the problem with the Ford trucks, they do in cylinder regens instead of the 9th injector setup like GM and Dodge are using. Mattd on here can give some insight on the Powerstrokes, he works on them all the time.
