Thor Forums

[howzball]

After having to take our coach in for a check engine light on a 6.7l ISL I asked what could have caused the NOX sensor issue and the service tech asked if I filled up at the bulk DEF pumps or used jugs.
I use the pump when it's available and he advised me to use jugs to possibly avoid this problem in the future.
He said it could have been the DEF sits in your motorhome longer than it does on most of the trucks that buy at the pump so it doesn't have a chance to go bad.
It did make sense but, does DEF really go bad if it sits for a few months? I never heard that before.

It turned out the repair was emissions related so, it didn't cost us anything since we're only at 16K miles but if anyone's ever heard of this I'll certainly stay away from the DEF at the pump. Some of these truck stop pumps are sketchy I must say, there's no telling what could be in the tanks.