Audi A6 C8 2019 - ADBlue No Restarting x miles

[jonnnnny]

Hey Everyone,

Hoping I can get some help with a problem that has been plaguing me since December with no luck from getting help from Audi or Independant garages etc.
In December during a 400 mile trip the error "No restart in 650 miles" came on. During my return trip I filled the adblue tank up as it was very empty (but the car did not warn me of this) so it took about 16 litres of Adblue. When I got home I took it into my local independent garage who do all the work on the car from me and found the injector was crystalised so they cleared this out in an alcohol solution and all seemed to be well after I got it back - until I was on another long trip where it came back but the counter was at "No restart in 170 miles".

As this error presented itself about 20 minutes later whilst still driving to my destination I was rear-ended but this has nothing to do with the problem but more so on why I didn't have the car until the 8th of February and there was a gap in time for context. I drove the car back home and the counter was not at around "No restart in 100 miles" - because of this, I bought an OBD11 to check codes etc (relevant further down the post).

When I got the car back from the body shop the error still presented itself and I read up that it could be crystallisation in the tank / on the pump / injector so I bought some of the Wyn's decrystilastion magic liquid which after putting into the car and a quick run on the motorway at high speed / high revs and the error went away but I still took it to Audi for a once over and they said there were no codes and no errors could be found or anything looking out of place.

So everything was looking good so on the 11th of February I had a work trip to go on which was bout 400 miles away, which for the most part was uneventful until I was pulling into the hotel the error came back and we were now at "No restart in 90 miles". I brought OBD11 with me so I scanned the codes and below is what I found:

Error from the 11th of Feb

 

So, after I got to the hotel, I had another bottle of the Wyn's decystiliation in the boot which I added to the car and went for a drive at high speed / high revs and low and behold the error went away. So I decided all was well. Few days go past on my work trip and my ABS vacuum sensor fails so I take into the local Audi Garage who replaced it, but also had a look at the Ad-blue problem but again as there were no codes or errors they said they can't do anything and everything looks great.

I then drive the car back home about another 400 miles with absolutely zero problems (but I mapped out all the nearest dealerships on my route just in case). So I thought that was the end of it, that's me now done close to a 1000 miles with it appearing once but going away shortly after.

Unfortunately today, the 24th of February I was doing a fair bit of mixed driving on the motorway (lots of traffic today too) and some normal commuting on normal roads for some errands, and on the way to one of my destinations the error came back and is now showing "No restart in 70 miles". So I drove straight home to keep the error fresh for the dealer but about 15 minutes late the error went away BUT the check engine light stayed ON which is the first this has happened. See below for the errors presented today:
 

First image of code P20FE00

 

Second image of code P20FE00

Second code.

So it looks like the same errors, but this time the ECU seems to have stored them despite every other time the error went away so did the codes.

Few points to raise -

• DPF Regeneration Cycle has not occured in a months, it used to go off every 500 miles when I parked up but I haven't heard it once since the errors started in December;
• The Adblue tank has not used any Adblue in over 1000 miles the tank has stayed at the same fill level the whole time which is 95%;
• The check engine light always goes away shortly after the adblue light goes away (except for the most recent case above);
• In case you missed above, this is a A6 C8 2019 without about 50000 miles on the clock;
• The PPM one of the NOXsensors seems to be off from the others - see below for an image with my foot almost all the way down on the accelerator and one with the car idle:

Accelerator pressed down.

 

 

Idle.

 

Anyone got any advice or seen anything like this? I currently can't confidently drive the vehicle and I am pumping money into diagnostics like there is no tomorrow but nothing coming from it. I am on the verge of selling the vehicle and buying another A6 as I absolutely love the car.
 

[jonnnnny]

3 minutes ago, jasonj said:

https://www.google.com/aclk?sa=l&ai=DChcSEwjHlf7q_sSEAxX3nFAGHQI1BecYABAAGgJkZw&ase=2&gclid=Cj0KCQiAxOauBhCaARIsAEbUSQRtGScNHNNvNv9MS3tN1XkjNVU33m_HFcfrd5EaILcl-SB1iCoYbqIaAnePEALw_wcB&sig=AOD64_1ciJfWfN3pDMDd-ui4HQuhNJCF0w&q&nis=4&adurl&ved=2ahUKEwjltvfq_sSEAxVHUUEAHcq2DzkQ0Qx6BAgWEAM

I have considered a delete but I've heard they are illegal? 

[Steve Q]

Well documented issue, you'll need to get it to a garage to get the system reset, sensor replaced etc

[bhuman]

Hey @jonnnnny how did you get it fixed in the end? A delete or new parts? 

My A4 B9 is currently sitting at 70m no restart and been quoted £395 to delete -still in two minds whether to have it properly looked at and potentially end up with a bill of £2k+ for new parts.