I bypassed the pre Heater all together and have not had any problems in minnesota yet

 

If by preheater you mean the grid heater, yes it should be working for that cold of temp.

 

Your time will come...

 

I was not refering to the grid heater, there is a seperate fuel pre heater element. Ive read a few times about them, so must be a somewhat common problem. the electronic connected fries completeley. Naturally, you have to buy the whole pre heater assembly and cant get just the electric contact parts. Long story short, i bought it, then realized i only needed the electric part, i cannibalised what i needed and planned on returning the part to the dealer. I ended up having a crisis of concience, and didnt keep any of it, i decided to go without.

Long story short, i am without pre heater element, and since the day of the post its been ok, were back above 0 degrees. On to the next issue, when i plug in, my block heater trips my GFI in just a few minutes.

 

Fuel heater parts are availible separately.
Cummins part numbers
heater element upper quad ring 3834185-S
heater strainer kit 3845400-S
heater element 3907766-S
cable harness 3843722-S