My company issued 2023 Ram Promaster has an issue with the cab filling up with raw gas fumes during hot weather. They are very over bearing, make breathing difficult and of course they are flammable. I've taken it to the dealership 4 times now over the past year. The first 3 times they've said they can't replicate it and they don't smell anything. One dealership did try replacing the evap canister and fuel tank pressure sensor but this did not fix the issue. Eventually I determined the source of the fumes myself. They are back flowing from the leak detection pump filter and I even have this on video. The 4th time I took the van back, showed them the video and raised a fuss so they gave me a brand new 2025 to borrow while they try to fix my work van. Well sure enough I have caught the 2025 loaner doing the same thing and I also have it on video and have a witness. This leads to me to believe this is a factory design flaw with the Ram Promaster vans. They are supposedly submitting this to their engineering department but I do not want this getting swept under the rug. If you look up emissions recall UB4 it appears they have had this issue for years but never truly fixed it. The manufacturer is getting away with putting dangerous vehicles on the road and not properly resolving the issue.
NHTSA ODI 11687011