Houston..we have a problem!

DEF warning with countdown

The 'DEF' or Diesel Exhaust Fluid system in Mercedes Benz sprinter vans, which is what our RV chassis is, plays a critical role in emissions control. What I'm learning is that DEF related faults are not uncommon and they can happen from a variety of reasons. This DEF emissions system was mandated for diesel vehicles I believe after around 2016. What it basically requires is that this DEF fluid has to be added to the vehicle every so often. There is a gauge in the dash console that tells you how full it is or isn't. This system is very sensitive to any aberration in fluid consistency, crystallization or other mechanical and electrical factors way beyond the scope of this blog.

When DEF related faults occur you're typically going to see the check engine light come on followed by a start countdown where after 10 vehicle starts you will not be able to operate the vehicle. I am not going to get into the logic of this or why this is necessary. Unfortunately it's the law.

I made a point of having this thoroughly checked out the first time it happened about a month before this trip and at that time it was because of a broken DEF line that had to be replaced. Great! The engine light went away. We're good to go..until we weren't.

So there we were, on Odyssey day 21. We're on our way to Waterton Lake National Park in Alberta when once again the engine light comes on followed by the dreaded DEF warning!

Obviously we could not continue up there, so we researched our location in relation to the nearest Mercedes dealership and made the decision to divert back to Spokane for servicing. The good news was they were able to take us in right away and diagnosed the problem as an apparent loosening of the previously replaced DEF line. This was repaired with no charge. We stayed overnight at a Best Western hotel which was within walking distance. We discovered 2 amazing restaurants also within walking distance so all wasn't lost except our planned stop at Waterton.

Well now we had to reboot the journey and figure out what we were going to do from here. I guess that is part of RV travel! You never think it's going to happen to you until it does!

Thanks for reading!

DrDave