I also read that there is a shared warranty cost between Cummins and FCA. It was a contributing factor combined with reputational damage that led Cummins to demand a change. We'll never know for sure what spurred it.
Beyond labor/parts there is NO WAY this hasn't hurt sales or put a black eye on the brands. A few units not sold among the hundreds of thousand? No biggie, but in the business world bad press is something they want to avoid. Just this last year the 2020 model had TV commercials and FB ads running on "the most loyal HD truck buyers". Look at the lengths they go through in marketing with durability talk. Especially in this segment of vehicles. They are marketed as tough, capable, and long lasting above ALL else.
I'm surprised the automotive media hasn't jumped on this harder. Even if there is a low incident percentage, it has a VERY HIGH impact in the enthusiast community. Everyday people that just needed a capable truck now have heard the name "CP4". The percentage of L5P owners that have heard the name "HP4" is likely far lower. Take me, for instance. I was a diehard GM lifer. Before this truck I bought a new 06, 12, 13, 14, 15, 16, and 2020 model GM vehicle. I didn't do good enough research on this truck but if I saw all this CP4 stuff before pulling the trigger I'd have an L5P, as god awful ugly and more expensive as it is, sitting in the driveway. Rona availability and the Cummins legend mixed with the new interior got this GM sycophant to sway, but it got lucky because I let my research guard down for whatever reason haha.
Right after I bought it I convinced my equally Ford lifer friend and instead of a Super Duty he ended up with a 2020 Cummins too.
Let's also be honest here too in recognizing that Ford and Chevy (GM) have loyalists and brand supporters that carry the flag all the way back to the 60's and prior in a much larger percentage. On the streets, Ford and Chevy (GM) buyers buy their HD diesels because they are Ford or Chevy (GM). Ram buyers buy their diesels because they are Cummins. Without the Cummins and it's legend (mostly based around durability), the Ram/MOPAR fanbois by themselves couldn't carry this pickup. Sales would plummet.
More of my ever devaluating $0.02c