So, my 2106 F250 diesel threw a code about low pressure from the DEF injector pump. When I brought it to the dealer to get it fixed they informed me that the DEF tank was contaminated with diesel so it wouldn't be covered under warranty. I have no idea how diesel got in the DEF tank. Yes, I know you are thinking I just screwed up, and I'm sure the dealership guys are thinking the same. I'm pretty sure I did not. First, the DEF filler is so small the diesel nozzle doesn't fit. Second, the DEF tank was less than 1/2 full. If I had filled it with diesel by mistake, why would it not be full? And if I had realized my mistake and stopped part way then I would remember. Also, I'm pretty sure I had filled the DEF tank not that long before (with DEF from a plastic jug, NOT from a gas station pump.) I was surprised it was only 1/2 full. The truck had been sitting for a bit while we were staying at home due to the COVID 19 crap.

It's driving me crazy how this happened. Any ideas? Has anyone else heard of something like this?

Thanks,
Ken

 

I just read this thread after searching for a similar problem. My tech said my DEF tank was contaminated....I asked "with what"? He said some other liquid. It's NOT diesel, but is probably contaminated from the previous owner. DEF goes bad and he probably poured in some old rotten spoiled DEF.
As for yours, what finally happened? They should be able to drop the tank and clean it out, and put in a FRESH new DEF and it will be good after clearing the codes.

 

Not too sure of the exact time period for storing DEF, but it does go bad and crystallize , learned that the hard way.