The DEF system in our newer trucks must function optimally in warmer environments rather than in colder ones, in my option. So in Alaska our longer winters probably equate to an increased amount of DEF issues compared to say trucks operating in Texas. My 2013 truck has been in for DEF related issues numerous times, some for replacing DEF injector and some apparently related to software bugs, but luckily all has been covered under warranty. Understanding that DEF will begin to ‘slush’ before it freezes and will ultimately freeze into a solid state when the fluid temp reaches just 12 degrees F requires a DEF heater system too. Which is just another point of failure of the DEF system. "The process of freezing DEF has no effects on its quality or performance" unless it's the fluid in your vehicle's DEF tank that freezes up...