Frozen exhaust fluid

Coalminer514

Member
Joined
Apr 29, 2019
Location
North dakota
TDI
05 Jetta TDI
Just got back from the dealership. It was negative 20 when I filled my def fluid and the miles didn’t reset. dealer said my def is froze and I will need to park in heated garage for 2 days and require a scan tool to reset my miles. He said no codes were active to force engine shutdown. I am now at zero miles left and can’t restart engine. I’m wondering if anyone has ever ran into this before. I live in North Dakota and car will always be parked outside. Also anyway to avoid this in the future because it will hit negative 20 here again! Anything helps. 2013 Passat se
 

Coalminer514

Member
Joined
Apr 29, 2019
Location
North dakota
TDI
05 Jetta TDI
They didn’t say anything about the heater not working which was my thought. On my drive back from dealership the countdown hit zero, then it went away and car runs fine now. I’m curious though does that heater run constant when the car is parked? On a day like today when the actual temp is negative 15 and my car sits outside at work for 12 hours is the def heater always running?
 

ZippyNH

Veteran Member
Joined
Apr 22, 2015
Location
Southern NH
TDI
2015 JETTA TDI SE
Typically def is melted as the heater runs (when and if it freezes, that's what HD truck companies say, and then say frozen DEF is a non issue)...bet with lots of short trips it melted a cavity around the element in the DEF.(or the heating element is burnt out.. maybe both).....
I would careful use an electric heater, with a thermostat built in....toss it in the trunk VERY CAREFULLY, or maybe even a heating pad with a blanket tossed over it...if I recall the tank in your model is under the spare in the trunk (so remove the spare for airflow)... (if it was a newer jetta with the tank largely in the bumper cavity, it might need a different tactic) let it run overnight...then if I can start the car the next day, problem solved...for now....if not...guess the car needs to be towed to a heated garage...let it sit, and maybe the system reset.
There were a bunch of thread's of I recall with people haven't DEF heater issues a few years back...and a few DIY solutions that were cheaper than a full tank replacement if I recall for handy owners.
 

ZippyNH

Veteran Member
Joined
Apr 22, 2015
Location
Southern NH
TDI
2015 JETTA TDI SE
Just reread it...looks like the countdown reset itself?
Sounds like a longer drive fixed it...just like so many TDI issues. These cars were made to be driven, and they thrive with longer trips...short trips are very tough on them.
Letting the run a bit more will surely help...if I remember the DEF heater works as needed, and of course ONLY when the engine is running.
I bet the heater element melted a cavity around itself...maybe ran dry..due to short trips (very bad)
Some fresh fluid, a longer Drive fixed it for now.
 

FXDL

Veteran Member
Joined
Oct 27, 2009
Location
Barrie Ontario Canada
TDI
2015 Jetta TDI with DSG
Keep the tank full at all times in the cold weather will help and also help stop condensation from forming in the tank which is not good.
I am always topping up for those reasons, in fact both in the winter and in the summer to cut down on condensation.
You will get condensation in the summer when warm/ hot day and cool nights, winter also as I park in heated garage for work and the car came from cold outside winter weather.
 
Last edited:

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
The SCR system is supposed to be able to deal with this. Supposed to. I think VAG's strategy seems to struggle, though.

In theory, the system knows how cold it is (plenty of inputs to find this data in the car), so it just turns on the heater(s) when required and doesn't attempt any DEF dosing when it knows the fluid is frozen. And it tries to keep the lines clear when you shut the engine off (the pump runs backwards to pull any DEF from the delivery line).

The CKRA's have had a lot of post Dieselgate fix SCR issues related to the system's logic for resetting the countdown as well as improper dosing during extended high speed (80+) driving. I am really not sure if they've ever really got it entirely sorted. Which is why, unfortunately, deletes are so popular.

Other than the injector/delivery line leaks, the CRUA and CVCA engines in the 2015 cars seem to have fared better post fix. And the leaks have nothing to do with any changes made anyway.

All the manufacturers seem to have had some teething troubles dealing with SCR in extreme temps. Why VAG continues to struggle with the CKRA I have no idea. I know MB completely revamped their entire SCR system on the Sprinters in 2014, and this dramatically improved their durability. The 2010-2013s were problematic (tank heaters mostly).

It is a great idea in theory. A post-combustion NOx reduction strategy, allowing less EGR, so letting a diesel engine do what a diesel engine does best, and run LEAN, which then also means less soot, so less DPF regens, which all equates to better fuel economy. The fact that the relatively large NMS Passat can come close to an ALH car on the highway MPGs is pretty impressive... it couldn't do that without SCR. But it sucks that VAG's SCR strategy evidently wasn't enough to keep them NOx compliant all the time, and worse, not even able to be improved upon sufficiently to allow the manual CKRA cars to get a pass :( But clearly the durability and reliability of the system in general is still quite suspect.
 
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