Originally Posted by upflying
I thought the pump failures were caused by owners running out of fuel which damages the pump from lack of lubrication.
While that could be a cause, it's certainly not the only cause.
In mid-2018, My brother was towing a smallish utility trailer from Denver to Louisville, KY with a 2016 GMC Denali 6.6 Duramax with 42,000 miles on it. Somewhere in KS, his truck just cut out and stopped. Towed to a dealership ... and CP4 pump failure. Between parts delivery and labor, this was a 3 week quoted job -- 2 weeks for parts, 1 week for the actual job. All under warranty. My brother traded it in on a 2018 GMC Denali 6.6 Duramax so he could complete his move.
This summer, he got a DEF failure that was probably due to a bad DEF tank sensor. That was it for him; couldn't trust his truck anymore and couldn't afford to be stranded on the side of the road again. Traded that in on a 2019 Ford Explorer ... the Ford dealership came and towed away his Duramax.
But, back to the CP4 issue, I think most of the failures were like my brother's: just random failures during normal driving. Some suggest off-brand diesel isn't as lubricating as Shell/Exxon/Big Brands. Some suggest that too much biodiesel causes lack of lubrication. Some suggest a lubricating additive is necessary. Some suggest the CP4 pump is inherently designed/manufactured poorly. And, so on. I don't pretend to know the true root cause.