Yaemish

A couple of weeks ago I receive the "1,000 mile countdown" to refill the AdBlue. I added 5 gallons and I know that sometimes the counter drops another 100 miles before it reads again. Despite driving a 2 hour trip each way on the highway, the countdown kept going and crossed the dreaded "600 mile countdown". My extended warranty expired ~ 10 days ago.

Doing a scan showed intermittent errors that didn't set a "check engine". The NOx was my primary concern as this applies to the AdBlue system. Codes are below;

P20EE00 - SCR NOx Catalyst Efficiency Below Threshold Bank 1 Catalyst 1 (Intermittent)
P017100 - Fuel Trim,Bank1 System too Lean (Intermittent)
P046C00 - EGR Sensor "A" Circuit Range/Performance (Intermittent)

I pulled the NOx sensor from under the hood and my ultrasonic cleaner and "Liqui Moly Diesel Fuel System Cleaner" to clean the sensor. Then did it again in fresh solution, compressed air, followed by a bath in rubbing alcohol, compressed air, and letting it dry overnight before the reinstall. I also disconnected the AdBlue injector to clean it, but it was already spotless without any buildup.

I was planning to do a forced regen and I stumbled upon a way to force the AdBlue level read in OBDeleven. Then I moved on to trying to force an in-place regen and the car kept aborting it with the message "exited due to reasons of safety". My research indicates that there are some conditions that need to be met in order for this to work. Perhaps I haven't met those yet.

I cleared the codes and drove for a bit while monitoring what I thought were some of the relevant values. A rescan showed the following codes;

P220200 - NOx Sensor Bank 1 Sensor 1 Circuit Low (Intermittent) - new
P220100 - NOx Sensor Circuit Range/Performance Bank 1 Sensor 1 (static) - new

I am worried that something is still "off" with the regen system and long term use will lead to it clogging up. I appreciate any expertise that others can chime in with.

I'd like to add I see the NOx sensor throws some crazy numbers at startup (65535 PPM) and then after driving I can watch it bounce around between 12 PPM and 70 PPM on what I think is the engine sensor (bank 1, sensor 1 and sensor 2). I never see any readings on bank 2, sensor 1 or 2 (I think this is the second sensor that sits under the car but I don't know for sure).

Live Data
soot mass calculated 25.36g
soot mass measured 20.02g
charge limit for service regeneration 36.34g
charge limit for field regeneration 23.12g
time since last regen 5.8 hours
fuel since last regen 16.82L (4.4 gal)

-Wes-

There's a lot going on there! Do you have any updates now after a week+ since the original post?

If your dash is actually doing a urea countdown, then it should reset after turning the car on, letting it sit for 30 seconds, then starting it. You can also reset it with VCDS. However, if it is an efficiency issue with the system or a bad pump, then it is a slightly different dash message, and it *will not go away* without fixing the underlying problem first.

How many miles on the car? The plethora of efficiency codes make me think that the catalytic converter for your NOx is probably on its way out. However, this usually starts with a "catalyst efficiency below threshold" error, which you can clear and it doesn't come back, followed by it eventually returning, and this cycle becoming shorter and shorter in terms of the number of miles accumulated between resets. Mine was on that path when I deleted it due to a recurrence of a urea pump failure that had already been replaced twice while under the scandal warranty.

DPF live data is completely unrelated; that system, at least, looks healthy to me!

'10Q7TDI_Prestige'

When I had crazy issues with the SCR system, it ultimately turned out to be a bad Nox sensor as the root cause issue. Thankfully, Audi replaced every other SCR parts item prior to figuring out it was just the stupid sensor.

FWIW, I have an OBD-Eleven, which was great for the little stuff and reading codes, but I compared the 'pro-level' access on that to what I can see with VCDS, and VCDS gives you so much more context and information when viewing live data, not to mention you can actually perform regenerations via VCDS, and a whole lot more. I bought VCDS due to the OBD-Eleven couldn't help me with my control modules issues and resolutions; VCDS is simply much better developed for the Q7's intricate systems and feedback loops. I keep the OBD-Eleven around just for proactive scanning, but if there's a problem, out comes the VCDS.

Yaemish

Sorry, I forgot to come back and revisit this. There was a bit to unpack and I got some help from one of the Touareg guys.

First off, if you come across this post because you filled your AdBlue and it isn't registering the fill up, there are some things to consider. When this first happened to me, I got the warning, filled it, and continued to get the warning. I suspect that the countdown does a check at some interval. I got my 1,000 mile warning and I filled it with 5 gal, and the countdown kept going. At 600 miles I got the additional message that the vehicle wouldn't start until I added the fluid. That made me nervous and I starting looking into why I was having issues.

I found that if you have a VCDS you can look at a lot of different settings that will help you clue into why you aren't getting the reset. I have an OBDeleven, and I was able to look at these settings but the documentation was lacking when compared to VCDS. If you are shopping between the two, I would say to go with the VCDS. In my case, I had a NOx1 code that was intermittent but it wasn't setting a "check engine". I believe that this was preventing me from running a proper regen (I'm not 100% sure because I didn't give it time to figure out if that was the cause). You have two NOx sensors that are part of the SCR system. One is under the hood, near the back of the engine. Remove the beauty cover and you will see it (the oxygen sensor is the sensor closer to the bumper and the NOx is behind it closer to the driver). In my case (and I suspect most cases) the NOx1 under the hood is the problem, it gets dirty.

I removed the sensor and soaked it in Liqui Molly Diesel Fuel Cleaner along with an ultrasonic cleaner. The cleaner shakes at a high frequency and probably helps a lot. I dumped the dirty cleaner and refilled with fresh cleaner and did it again. I also poked the little holes with a needle. Once it was done cleaning, I emptied and filled it with rubbing alcohol and ran the machine again. I removed the sensor, sprayed it out with compressed error, then washed again with new rubbing alcohol and followed with another blast of compressed air. Then I let it dry over night. I don't know if the alcohol was required, but it will help with evaporation of any residue that may have been left on the sensor. Does it really matter when that sensor is going to get hot? Probably not.

I put the sensor back in, but here is where I used OBDeleven to force the tank level to be reset. I don't know if it played a part in the regen running. Using OBDeleven, you go into "Engine" and change the "Service" to "End of Line" and then go into "Security" and choose the first security code (I remember the number 2 and 7 in the code, I think it was at the top of the list). Then you go into "Basic Adaptations" and there should be one for "SCR Reset". After you do that and cycle the ignition, the AdBlue countdown was cleared.

I used the OBDeleven to watch the regen occur and will no monitor that system until I am deleted. From the same "Engine" module, you can view "Live Data". Do a search for "soot", there is a monitor for "measured" and "calculated". You'll want to select those as well as the "NOx Sensor" values. I can't remember off the top of my head, but there is also a value that determines the soot level that a moving regen will occur. You also have the ability to do a stationary regen, but if the soot exceeds a specific value, the system will not allow you to force it.

In order for a regen to actually start (while in motion), you'll need to be at full operating temperature and have met the conditions for soot volume. You must also have more than 1/4 tank of fuel, otherwise the SCR system will not start a regen. I hope this helps others.