I have a 2024 6.7HO pulling a large trailer, DEF warning comes on show 498 you need to fill, but the %gauge is at 71% so I add DEF and it won't even take 2.5gals ! They is an on going issue. I'm unhooked and driving without trailer and DEF is say 423 fill and my % is at 68 left in tank.
Anyone have an idea?
PS. My 2021 6.7 was spot on DEF gauge also show correctly when towing.