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NOx / AdBlue problems on 3.0 TDI

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Yaemish

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Discussion starter · #1 ·
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) - same as before
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 other can chime in with.

I'd like to add I see the NOx sensor throw 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).

soot mass calculated25.36g
soot mass measured20.02g
charge limit for service regeneration36.34g
charge limit for field regeneration23.12g
time since last regen5.8 hours
fuel since last regen16.82L (4.4 gal)
 
#4 ·
Ok.... I just re-read your post off a computer instead of off my phone... so I have some questions for clarification.
Do you have VCDS or only ODBcrap? It sounds like no VCDS to me, so that will make things interesting.
Why are you talking about DPF regens when you're trying to address NOx codes\regens? Neither DEF system nor NOx sensors have anything to do with the DPF regen.
Also, based on your values, you can no longer perform a standing regen as you've exceeded the limits.... a driving regen is your only option at this point.
soot mass calculated25.36g
soot mass measured20.02g
charge limit for service regeneration36.34g
charge limit for field regeneration23.12g
Click to expand...
 
#5 ·
I just looked it up..... you're "almost" there assuming that you don't have any other faults impeding a normal driving regen.
And you should probably tell us some details about what it is that you actually have if you want help. (3L TDI 10 days out of warranty isn't very helpful)
Code: 
The start of normal driving regeneration is 27 grams.
 
#6 ·
I sometimes wonder reading yet another issue with the emissions equipment on the TDI ,how the long distance tuckers ever stay on the road running their diesels 24/7. Why not use what they use in a smaller version to get these cars more reliable. Can't be rocket science. I'm sure VW isn't putting any more thinking about diesels anymore, too bad.
 
#7 ·
Don't worry... Class 8 vehicles have their struggles too... but they are also being used in way more favorable conditions (long hwy drives, lots of load\heat generated, way more acceptable fuel\def consumption, etc). Plus, their emission regulations are probably more relaxed (I'd have to look this up, but I'm assuming here)
 
#8 ·
I'm sure you are correct about relaxing the requirements,which seems odd since these monsters get about 6-7 mpg meaning they are burning 5 times the gallons of fuel per mile as a car diesel. US regulators were trying to teach VW a lesson and it worked, no more diesel cars.
 
Discussion starter · #11 ·
@SaVAGeSoot, I believe that I did stumble upon some of your posts when I was researching this. There was a lot to read in a relatively short time, so I don't completely understand all of it.

The reason that I am chasing the NOx problem is because of the full tank of AdBlue not resetting the countdown. I drove almost 500 miles without the reset. I found the NOx error once I started getting nervous. I stumbled upon some posts in the Ross-Tech forums that indicated that the NOx problem was related to the AdBlue message not resetting.

I did use the OBDeleven (and yes, it is crap and I made the wrong choice in purchasing it) to kill the countdown and read some of the live data.

Now my concern is that a faulty NOx sensor may be present and it will lead to a clogged system. I tried cleaning the probe; I'm not opposed to throwing $400 at a new sensor. But that is a bit of money to waste of this is guesswork and the sensor is't really bad. My thought is that if a regen occurs, I can breathe a sigh of relief and continue monitoring the problem. If it doesn't happen, I need to park it and figure everything out immediately.

Thank you all for the help. I understand if you are hesitant to provide additional help since I only have OBDeleven. I'm sure that I can find values as requested, it just takes some time with this POS product.
 
#12 ·
I'm not hesitant do provide anything. I just want to know what we are talking about.
What year, make, model, mileage do you have?
Can your POS tool do a system scan?
Can you provide that result?
What active faults do you have?
Can you look up specific MVBs with said POS tool?
I can give you list of things to look at once I know what you have, etc.
 
#14 ·
Yaemish said:
I'd like to add I see the NOx sensor throw 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).
Click to expand...

High numbers on startup is normal. NOx sensors work very similar to O2 sensors and require exhaust to be over 300c to start reading correctly. NOx will bounce around a bit on sensor 1. Sensor 2 (rear) should read pretty stable as the SCR should iron out all the NOx if the Def system is working correctly.
 
Discussion starter · #15 ·
Thank you again to all the people taking the time to help me. I do appreciate it and I hope that this work is also helpful to someone stumbling upon it in the future.

@SaVAGeSoot, to answer your questions;
What year, make, model, mileage do you have? 2012 Q7, 108,000 miles
Can your POS tool do a system scan? It does a complete scan as it relates to trouble codes, even the ones that do not trigger a check-engine light. Some of the more complex scan outputs that I saw in the Ross-Tech forum are not possible. However, just about every piece of information that the VCDS pulls, can probably be read but it will be a matter of finding the specific info. I think I know where to find those specific values that you will want to see.

Yesterday I had two that I cleared and have not yet return.
P220200 - NOx Sensor Bank 1 Sensor 1 Circuit Low (Intermittent)
P220100 - NOx Sensor Circuit Range/Performance Bank 1 Sensor 1 (static)
Can you provide that result? Today's scan had zero fault codes, this after driving for ~40 minutes.
What active faults do you have? None
Can you look up specific MVBs with said POS tool? I don't think it can read the MVBs as direct as the VagCom does, but I can probably find them in the live data if I know the names. I am going to guess that the OBDeleven app is a backwards engineering of the Ross-Tech and meant to be more user friendly for the masses. The company fell a little short with the execution and very short with the documentation and support forums.

I drove today and monitored what I think might be relevant values. A regen did occur, I watched the "soot mass measured" and "soot mass calculated" drop steadily from values in the 30's down to 3.32 g and 7.64 g respectively. I can confirm that it was a regen, the "time since last regen" was reset and down to just a few hundred seconds.

As for NOx sensor readings; I think the app may have a bug. There are a few different names for these values that I can read from. One such selection lists them as "NOX sensor bank 1 sensor 1" and "NOX sensor bank 1 sensor 2" (the NOX sensor bank 2 reads as "not installed"). When I read the from this named value, I see sensor 1 (assumed to be under the hood) jump around a lot. It spikes to 65535 ppm (when it is high it is always this number, probably has something to do with software engineering and 16-bits). Based on the "16-bits" thing, it probably isn't 65535 ppm, it is a null value and can't be trusted. I do see it go as high as 799 ppm.

I did find another name to read these two sensors from and the numbers look a little more realistic. Unfortunately, I didn't notice this additional selection until the end of my drive. Next time I take measurements, I'll be sure to change to this view instead.

These are the corresponding NOx1 and NOx2 readings from while it was doing the regen. I'm not sure if they will be of value.
NOx177501120538799357
NOx22027134853117
 
#16 ·
OK, so that should mean that you have a CATA engine.....
I don't know anything about your ODB11 POS, but I can give you all kinds of labels from VCDS to attempt to find in your tool.

Here's some to start you off, but based on what you've said, I don't think you have a DPF regen issue yet.....
See how many of these you can find and post your values
Code: 
  IDE00432   Particle filter: time since last regeneration 5725 s
  IDE00433   Particle filter: oil ash volume 0.25 l
  IDE00434   Particle filter: soot mass calculated 11.74 g
  IDE00435   Particle filter: soot mass measured 11.75 g
  IDE00436   Particle filter: kilometers since last regeneration 73285 m
  IDE00584   Distance driven since erasing DTC memory 13147 km
  IDE00603   Number of driving cycles since erasing DTC memory 255 
  IDE01922   Vehicle distance driven 184555 km
  IDE03386   Long-term adaptation of reduction agent dosage 0.90 
  IDE05857   DPF statistics: current measured charging rate 0.1514 g/km
  IDE06983-MAS05392   Diesel emissions re-treatment: status-Average distance between DPF regenerations 906 km
  IDE07197   Average reducing agent since lest filling 1.06 l/1000 km
These will provide some idea of the health of your system.
It's also worth looking at your Readiness Status as it is also a tell-tale sign of some things....

Code: 
Readiness Status: 00000000 00001111 11101011 00000000
MIL Status: MIL OFF
Comprehensive Components: Passed
Fuel System: Passed
Exhaust Gas Recirculation: Passed
Number of EOBD-related DTC(s): 0
 
#17 ·
One more thing... instead of just posting a simple code and description, view all the FF data associated with it... there's lots of good info in there.... here's a sample of one of my past codes as an example
Code: 
9570 - NOx Sensor 2 Bank 1 
          P229E 00 [104] - Electrical Malfunction
          Intermittent - Confirmed - Tested Since Memory Clear
             Freeze Frame:
                    Fault Status: 00000001
                    Fault Priority: 2
                    Fault Frequency: 4
                    Mileage: 170693 km
                    Date: 2023.02.06
                    Time: 06:46:32

                    Engine RPM: 1271.50 /min
                    Normed load value: 55.3 %
                    Vehicle speed: 53 km/h
                    Coolant temperature: 79 °C
                    Intake air temperature: -2 °C
                    Ambient air pressure: 970 mbar
                    Voltage terminal 30: 14.760 V
                    Unlearning counter according OBD: 30
                    NOx sensor 2: NOx concentration: -100 ppm
                    Com r Lam Lin Rec Cat2 Ds: 0.9150
                    NOx sensor 2: feed voltage: 14400 mV
                    Target value of heating temperature of NOx sensor 2-Bits 0-7: 1
                    Com st N Ox Vld Cat2 Ds-Bits 0-7: 0
                    Exh st Lam Stat No Cat2 Ds-Bits 0-7: 0
                    Exhaust gas temperature sensor 4: 307.5 °C
 
#18 · (Edited)
SaVAGeSoot said:
It's all about politics..... The Shipping Industry pollutes more than any other ICE out there and they are literally allowed to burn garbage 24/7/265
Click to expand...
I think it’s mostly local regions trying to reduce local smog in dense urban areas with poor air quality like southern California… very little interest political or otherwise in global or rural emissions. In that context the rules make sense and work- the air in LA when I was a kid burned my eyes and throat just driving through on a road trip, it’s not like that anymore. It was a massive public health disaster they were actually able to fix.

Fun fact: when I moved to northern California a decade ago everyone told me about the famous "Tule fog" and how foggy it was around Davis and Sacramento. Nope, it wasn't foggy at all, ever- I never once saw this supposedly constant fog in years. It had been caused by NOx emissions serving as cloud condensation nuclei (CCN), and reduced NOx emissions have virtually eliminated the fog.
 
Discussion starter · #19 ·
I was able to get most of them. If I do see another NOx code, I can manually get most of what is listed as well. I just need to seek them out.

Code: 
Particle filter: time since last regeneration 1176 s
Particle filter: oil ash volume 0.27 l
Particle filter: soot mass calculated 7.94 g
Particle filter: soot mass measured 4.10 g
Particle filter: kilometers since last regeneration MISSING
Distance driven since erasing DTC memory 18.02 miles
Number of driving cycles since erasing DTC memory 1
Long-term adaptation of reduction agent dosage 1.0
DPF statistics: current measured charging rate 0.1564 g/km
Diesel emissions re-treatment: status-Average distance between DPF regenerations MISSING
Average reducing agent since lest filling 1.17 l/1000 km
As for readiness, I had cleared codes earlier today and I don't think I have driven enough for all of that information to populate. Say... nobody would happen to know a way to "force readiness"? At least display it once the vehicle is started and before a scanner is connected. So far, I think it looks like there may not be a NOx problem. Maybe the cleaning worked.

Image
 
#20 ·
There you go... Now put a few miles and drive cycles on it. You can't force readiness, but I can guide on on specific drive cycles once you show me the byte values like I listed above.

The good news is your DPF and regens are just fine and working properly. You need to drive a little for your DEF dosage to adjust as it's now reset.
 
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