DEF line froze and threw code

[Bluetick]

It's been mostly in the 20s where I'm at. I don't drive my Ram 3500 every day. And more short hops than I should. I was driving last week when I got a check engine light. The code revealed it was the DEF line. Turns out it was frozen. After two days in a heated garage, and a thorough cleaning of the injector it was working again. Which leaves me with a lingering question. Why didn't the DEF system's heater kick in?

 

[06 Dodge]

It's been mostly in the 20s where I'm at. I don't drive my Ram 3500 every day. And more short hops than I should. I was driving last week when I got a check engine light. The code revealed it was the DEF line. Turns out it was frozen. After two days in a heated garage, and a thorough cleaning of the injector it was working again. Which leaves me with a lingering question. Why didn't the DEF system's heater kick in?

My understanding is that DEF will not freeze until it 12 degrees or colder, I'm surprised to hear it did so in the 20's, in fact my truck has sat for a few days here at my house not even being started with temps in the mid 20's and not have any problems with frozen DEF and recall another owner over in ID who while elk hunting in the Mountains with over night temps below 20 degrees for a week did not report of having frozen DEF...

 

[Bluetick]

I misspoke when I said it's been in the 20s. That's daytime temps. The week this happened it had been going down into the low teens and into single digits at night. Then swinging back up in to the 20s. And that line was definitely frozen.

 

[18CrewDually]

The heating element is in the bottom of the tank. The "heat" can't get up the frozen lines going to the injector. Atleast not as fast as you would hope.

 

[cnovel]

whats def ? i think mine fell off on the rough roads i travel for work

 

[crash68]

Is it a line that froze or a more likely culprit that the DEF injector nozzle might be clogged up. The latter can happen if the exhaust system doesn't get hot enough to evaporate the DEF off properly. Not to say that a line didn't freeze but the nozzle is probably more likely.