P204 and P20EE

[14TDiMan]

Well, I was on my way to Florida when the check engine light came on and a adblue fault message came on in the message center warning of a 200 mile range before shutdown. Stopped for fuel and went ahead and added 2 gallons of Adblue. Turned around after clearing the codes and the CEL stayed out with only the orange def bottle and wrench light in the message center. Then the warning message went out and no CEL. Thought maybe the def tank was low and now it was meeting conversion efficiency. Turned around toward Florida and made it 20 miles before all the lights and messages came back. Went ahead and drove home. Luckily we were only a hundred miles into the trip. Inlet Nox sensor was replaced about 5k miles ago. Going to the dealer in the morning to drop it off.
Just looking for any advice based on experience with what the issue may be? I am thinking the def header(sending unit) may be at fault or maybe a bad outlet Nox sensor.(If equipped?)
Thanks for any advice, insight or help.

 

[740GLE]

If anything with the DEF system fails it'll throw tons of warning of no start in XXX miles, there's 3-4 failure modes of the DEF systems and they all need to work in order for the ECU to be happy.

A simple tune can rid you off all DEF systems and possibly stranding you on the side of the road in the middle of a road trip.

 

[trentstafford]

Check if you have the extended emissions warranty. I had a faulty/dirty Nox sensor, brought it into the dealer and got it repaired free of charge. Enter VIN Here

 

[14TDiMan]

Yes I do have the extended emissions warranty. Just got the car back from the dealer. They gave me a loaner and drove the vehicle (with my permission) for a few days after testing everything (all components passed)in the Adblue system. The car never produced another code or error message. The only thing they did after testing the systems was a hard reset of the modules, clearing all the learned parameters. The tech put about 120 miles on it over the course of the week.
I picked up the car and drove it on a 250 mile round trip with no issues other than lower than normal (33mpg) fuel economy. Fuel economy seemed to get back to normal (40+) the last hour of the trip. Cruise was set at 75 for the entire trip.
The service advisor and I used to work together back in the day so he let me go behind the desk and look at the VW warranty history. When the vehicle was released for sale the dealer that did the recall only updated the modules with 2 new software packages. The latter software upgrade deals specifically with Adblue errors after driving on the highway for an extended period of time, which is exactly the scenario in which the codes and error message set. I guess it did not work. In addition, the def tank heating element was replaced along with a boost pipe.
Time will tell. I am going to just drive it and see what happens.

Anyone with a similar experience who wants to share their outcome?

 

[watatrp]

I had some similar problems. Never got to the engine no start but within 20 miles. I stopped to refuel and the warning went off. Took it to the dealership. They had previously reprogrammed the adblue system and that didn't seem to help. They had it for over a week and ended up changing the rear nox sensor and the nox catalyst. I have not had it on a road trip since but no warnings yet with local driving. I understand that this problem pops up more when driving over 70 mph for extended periods of time. Mine would never show up until I had driven 75-100 miles at speeds over 70 mph.

 

[14TDiMan]

The Nox sensor was replaced 5k miles ago. The SCR and DPF are still original to the car. I drove 122.4 miles in each direction with 115 of those miles cruising at 75mph. When my CEL and Adblue warning came on last Sunday I had driven about 85 miles.
We will see what happens with the system. I will keep updating the post as I stack up miles or if the issues come back. Real test will be in two weeks when I attempt the trip again.