On November 2, 2015, the Environmental Protection Agency and California Air Resources Board informed Volkswagen Group companies that my Model Year 2012 3.0L Turbo Diesel Injection (TDI) vehicle did not comply with Federal and California emissions standards. In the approved emissions modification, my authorized Audi dealer claims to have removed the software that reduced the effectiveness of my TDI's emission control system and to have installed new emission control software designed to function effectively in all normal driving conditions. NOTE: this "Fix" that was devised to meet emission standards was never actually tested for "vehicle reliability, durability, performance, drivability or other driving characteristics", and by their own account would consume 40% more DEF (https://www.audiusa.com/en/complianc...l-information/), meaning it's stressing the emissions system 40% more than designed.

Since the TDI Modification my 2012 Audi Q7 TDI is having constant emissions system faults with 200 mile shutdown ransomware programming, and repeated replacement of the same components. It has rendered the vehicle as unreliable and now unusable unless I keep paying for Audi's "Fix". My vehicle had no such issues prior to the TDI modification and received all regularly scheduled maintenance at my authorized Audi dealer. I have compiled all my service records including the TDI Modification (7/26/18) then 9 emissions system failures (7/3/19, 11/12/20, 2/2/22, 6/27/22, 4/10/23, 9/14/23, 2/6/24, 5/2/24, 1/8/25). Currently, my authorized Audi dealer states that again emissions component replacement is needed, a part (rear nox sensor G687) that was replaced 4/10/2023 just 20 months ago for the second time since 11/12/2020. This failure to deliver a reliably working vehicle has already cost me considerably, so Audi has disabled my car with shutdown programming, taken it hostage needing proprietary Audi service, and are now demanding ransom to make it temporarily usable.

If you are experiencing similar issues join this thread as it seems like it's time for TDI class-action lawsuit Act II. I've already communicated with my authorized Audi dealer and Audi USA by requesting a written resolution plan from Audi’s Region Case Manager before escalating, which included the specific remedies I am seeking (repair, reimbursement, or buyback) but their response is "the vehicle is no longer within the applicable manufacturing warranties" so I just filed a BBB complaint against my authorized Audi dealer. Next, I will file a complaint with the State Attorney General’s Office: Many states have lemon laws or consumer protection divisions and the Federal Trade Commission (FTC): They may investigate deceptive practices.

If necessary, I'll engage an attorney specializing in consumer protection or automotive cases. Alternatively, I'll consult attorneys experienced in automotive defects, class-action lawsuits, or warranty law. Resources such as the National Association of Consumer Advocates (NACA) can help to find a qualified lawyer. Legal grounds may include:

• Breach of Claims: Audi may be failing to uphold the terms of its claims if the TDI modification is causing repeated failures.

• Unfair Business Practices: If Audi’s modification rendered your vehicle unreliable, this could fall under deceptive or unfair trade practices.

• Consumer Protection Violations: Federal and state laws protect consumers from fraudulent or harmful practices, and Audi may have violated these protections.

• Product Liability or Class Action: Explore joining an existing class action or filing a new one if others are experiencing similar issues.

Finally, media and advocacy are needed to publicize this case through media or consumer advocacy groups (e.g., Lemon Law Help) can increase pressure on Audi to resolve the matter fairly. Joining forums or groups, like this one, where others share similar experiences may strengthen our position.

 

While not the norm, you are certainly not alone in the repeated components failure of the selective catalyst reduction (SCR) components. I had a major failure about every 18 months post-modification on my 2014 Q7. I had to drive 400 miles (one way) to the nearest dealer for repairs, which took them between a couple days and a couple weeks. While I did receive a loaner vehicle each time, this resulted in 1,600 miles of travel for each event! I eventually reprogrammed the vehicle to bypass the system. That was not an ideal solution, but preferable to having an unusable vehicle.

 

While your car was still in warranty, well, yeah, there actually was a buyback /lemon clause you could have taken advantage depending on how much time your car actually spent in the local Audi shop, but all that warranty coverage/liability stuff on Audi's part is now done, and you are simply overpaying for incompetent and overpriced services by taking your TDI Q7 back to any 'Audi Stealership'. That's really just their business model; taking advantage of Audi owners, and you are being taken advantage of by them.

I'd say your thinking your TDI is a lemon likely has a lot more to do with the relative incompetence of the dealership that's working on it, although if you really want to understand what goes wrong with these TDI motors, and approximately when things are expected go bad, there's a great video on this topic. Search for Audi Q7 (4L) - Different Car Review video. It'll also show you the generic, known problems of the 4L Q7 chassis in general, which you definitely need to know about.

I'm currently at 130k miles on mine, and it's perfect. This is a great vehicle & powertrain, but if you don't know anything about these TDIs and what goes wrong with them, then you put yourself at a great disadvantage, as they can sure be frustrating when you are trusting and paying excessively for an Audi dealer to do right by you. Unfortunately, that's not exactly how they roll at the Audi 'Stealer'.

As example, my '10 TDI started doing very much the same with the countdown to no-restart (Adblue remaining estimated) coming on and then it began jumping all around for no apparent reason. What did Audi dealership do? Well they systematically started replacing the parts in the reductant system based on their GFF decision-tree based fault finding matrix, as the underlying problem didn't throw a fault code to clue them in to exactly what is causing that odd symptom to occur. In the end, I had a completely new reductant system, which of course didn't fix the actual underlying issue driving that warning message, which was in fact, simply a bad NOx sensor in the exhaust, which is what sends feedback to the controllers for the reductant system. So after replacing literally everything else, then they replaced a NOx sensor too, and voila', it was fixed! That was all done under warranty, btw, so no sweat off my brow whatsoever. I was quite happy for their relative incompetence.

Importantly for you, there are two NOx sensors in your exhaust, and while they perhaps did replace one prior, it may not be the same one this time.

Realizing you are disgruntled and want to blame Audi, but it's simply that the dealer service departments suck at troubleshooting and exist to print money for the dealerships, which they are quite competent at.

If you learn nothing else, don't take your used, out-of-warranty, Q7 TDI back to the Audi Stealership unless you simply enjoy overpaying and being taken advantage of. It's not the car. You need to educate yourself and also take the proactive steps to protect yourself since you don't DIY services/repairs on your car. Knowledge is power. Reasons why you could experience multiple sensor failures on the same sensor over a shorter period of time include incorrect installation or wire routing/protection issues, rodent damage to wiring, other problems within engine or products introduced leading to the exhaust sensor element being damaged, extremely cold climate, offroading your Q7, and simply bad luck/internal failure, etc. They generally can last for a very long time otherwise unless they were damaged during the installation. Do yourself a favor here and go lookup that video I referenced earlier, and then there's another video by DCR specifically on the Gen 1 TDI engine in your Q7 that really will open your eyes; at least I hope so.

Best, and good luck...those NOx sensors are super expensive when you buy/install them at the Audi Stealership.

 

I've already been to two non Audi service centers and they can't service the issue because of the proprietary Audi programming around this issue. Both have told me to bring it to the Audi Stealership.

 

Given the limitations of your jurisdiction on modifying the car to make it reliable again, you should definitely push for a buyback of this particular car. Whether other vehicles of the same class are experiencing similar issues post-"fix" to yours bears no relevance if your car is in repeated failure mode.

 

I've had zero issues with the reductant system post-warranty, but Audi techs did their normal fumble-stumble replacement of the reductant system piece-by-piece until they had replaced the whole thing; that still didn't fix the underlying issue triggering the NO-RESTART in dash to bounce around randomly on the mileage to no-restart, etc. It turned out to be the NOx sensor(s) that was bad and causing that issue.

Did I care that they were completely inept? Heck no, as I got a brand new, complete reductant system as a result of their ineptness. That's both the curse and beauty of the the TDI settlement warranty. My whole reason in buying this particular 'buyback' Q7 was the full remaining 4yrs/48k miles on it.

On your car, if you are past the 1yr mark from the last time they worked on your reductant system (parts warranty, etc.), then you are simply out of luck trying to get a dealer to do anything for you. It sure does sound like you got a bad NOx sensor in the exhaust, which sounds like it shouldn't be related, but believe me, it is. I've got the warranty repair receipts to prove it. Problem is, there's no direct fault code thrown by car, so the Audi techs just have to go through their internal decision-tree matrix (GFF - Guided Fault Finding) based on the symptoms they can observe, and that GFF, in turn, tells them to verify/check/replace a part then retest, rinse & repeat through the reductant system.

If that No-Restart message popping up randomly/showing you very low miles to no-restart instantly, etc.; that's a bad sensor almost 100% certainty. Look carefully over your records to see if one or both of your car's NOx sensors got replaced during the warranty.

We bought two Q7 TDIs (a '10 and '15), and both required at least one NOx sensor replacement before 120k miles mark. Also, for the record, our TDIs have been fine just refilling the reductant tanks when doing annual oil service. There is only one time I can recall ever needing to add reductant fluid before hitting the oil change, and that was driving in the mountains quite a bit. Towing would also increase reductant consumption, etc. I think your logic is flawed in regards to how much reductant is being sprayed being equal to increased wear on that system. You are much more likely to have problems and higher consumption in general if you fill the system with low quality reductant, as this car is calibrated for the high purity stuff. You can still buy the name-brand, high purity Adblue for $13 per 2.5 Gal jug at Sam's Club, for example, so it's not expensive to fill it properly.

 

adblue:Fault! No restart in 150 miles!


The following are the services performed on the vehicle in regards to the DEF (AdBlu) fluid and emissions system starting with the Dieselgate court ordered Emissions Mod:

2018-08-02 PERFORM23V2 TDI MODIFICATION 02
PERFORMED CAMPAIGN SERVICE 23V2 - TDI MODIFICATION - CRIT:
02 . REPLACED BANK 1 SENSOR 4 EGT SENSOR AS PER ACCESS CODE 2356299
PARTS- QTY - - - FP - NUMBER- DESCRIPTION
1 4L0-298-099-AX CONV. KIT
-1 4L0- 298-099-AX CORE RETURN
2 G-052-910-A4 UREA
1 4L0-010-023-C EMISS MOD
1 059-010-533-BB TDI EMISS
1 059-906-088-CC SENSOR

2019-07-03 CUSTOMER STATES CHECK ENGINE LIGHT IS LITE ON DASH There are Refill AdBlue warnings in the cluster.
The warnings appear approximately 1,500 - 2,500 miles after the last top-off. When the AdBlue tank is refilled, the
vehicle will only accept approximately 1-2 gallons of reductant. When checked manually, the active tank is 50% full
and the passive tank is full. There are no reductant system fault codes stored. The reducing agent transfer pump
V436 may be faulty. The vehicle cannot pump AdBlue from the passive tank to the active tank. Cars in hot weather
regions are more prone to this issue.
PARTS- QTY - - - FP - NUMBER- DESCRIPTION
1 4L0-131-901-B PUMP

2020-11-12 CUSTOMER STATES CHECK ENGINE LIGHT IS ON. ROAD TESTED, RAN VEHICLE DIAG AND FOLLOWED
TEST PLAN. R/I THE REDUCING AGENT INJECTOR TO VERIFY FLOW RATE - FOUND RATE BELOW SPEC
(INJECTOR CLOGGED) R/R THE FAULTY INJECTOR AND RETESTED. FILLED/VERIFIED REDUCING AGENT
TANK AND ADAPTED VALUES. RAN SYSTEM TEST TO VERIFY CAT FAILURE (CLEANED OUT PORT) SYSTEM
FAILED. R/R THE SCR NOX CATALYST. R/R 3 BROKEN STUDS, DRILLED OUT AND REPLACED. R/R THE REAR
NOX SENSOR WITH MODULE 9 SEIZED IN CAT DAMAGED REMOVING. CLEARED ALL DTCS AND RESET BASIC
SETTINGS. ROAD TESTED CHKD OK.
PARTS- QTY - - - FP - NUMBER- DESCRIPTION
1 4L0-254-400-AX CATALYST
-1 4L0-254-400-AX CORE RETURN
1 N-911-308-01 NUT
1 4H0-131-113-A VALVE
1 3C0-253-725 CLIP
1 7L5-253-115-C GASKET
1 059-907-807-T SENSOR
1 1K0 -253-141-J CLAMP

2022-02-02 CUSTOMER STATES CHECK ENGINE LIGHT IS ON PERFORMED RESETTING AD BLUE REDUCING AGENT
INDICATOR AGAIN, SEND GFF, ROAD TEST VEHICLE SYSTEM CHECKED OK.

2022-06-30 CUSTOMER STATES ADBLUE LIGHT IS STILL ON AFTER REFILLED
CUSTOMER STATES CHECK ENGINE LIGHT IS ON Adapted reducing agent tank values and performed extended
road test, vehicle is now operating as designed when compared to a vehicle of similar spec.

2023-04-12 CUSTOMER STATES HE GOT A AD BLUE FAULT ON HIS DASH BOARD. PLEASE CHECK AND ADVISE.
top off ad blue.
CUSTOMER STATES CHECK ENGINE LIGHT IS ON. PLEASE CHECK AND ADVISE.
04/10/23 14:22:29:US/EasternJeff DendelOpen: Consultant in ProcessWorkshop Findings: P20EE00: SCR NOx Catalyst
Efficiency Below Threshold Bank 1 Catalyst 1 P20F400: Reductant Consumption Too Low P207F00: Reductant Quality
Performance.
04/10/23 14:22:29:US/EasternJeff DendelOpen: Consultant in ProcessAdvised tech to perform the test plan and if the spray
test passes recommend to replace NOx sensor #2. After this work through the test plans for the P207F and P20F4 faults,
once successfully completed the faults should go sporadic and you can clear them. Thanks, Jeff

CHECK ENGINE LTE ON REDUCTION INJECTOR-N474, G687- REAR NOX-2....ADD BLUE BOTTLE TO START.
open case #3051404 was told to replace g687 nox2 rear, injector nozzel n474..top off ad blue reset light...must drive at least
500 miles to reset monitors.
PARTS- QTY - - - FP - NUMBER- DESCRIPTION
1 059-907-807-T SENSOR
1 4H0-131-113-A VALVE
1 300-253-725 CLIP
2 GUS-052-910-A3 UREA

2023-12-30 CUSTOMER STATES CHECK ENGINE LIGHT IS ON. Found multiple DTCs. Following test plan, recommend replacement of
EGT sensor 4, and Adblue injector. Also topping off ad blue and performing DPF regeneration test plan.
CUSTOMER STATES ADBLUE FAULT NO RESTART IN 200 MILES IS BACK ON-JUST HAD SERVICE IN ARPIL
Add adblue and adapted adblue level.

Check engine light is on. Found DTC for EGT Sensor 4. Check and found EGT sensor 4 has an electrical malfunction.
PLEASE ADD THE ADD BLUE Recommend replacement of G648 EGT sensor 4. CUSTOMER NEVER CAME BACK FOR
REPAIRS OR HAD OT EB CLOSED

2024-02-22 ADBLUE FAULT IS BACK. C/S WILL NOT START AFTER 150 MILES.. WAS NI SERVICE FOR THE SAME CONCERN IN
APRIL AND SEPT.
REPLACED ADBLU INJECTOR, CONNECTOR AND WIRING. CLEARED FAULTS AND ROAD TESTED, OK.
PARTS- QTY - - - FP - NUMBER- DESCRIPTION
1 4H0-131-113-A VALVE
1 3C0-253-725 CLIP
1 3С0-253-115-А GASKET

Adblue light Recommend flushing adblue and replacing adblue injector. REPLACED ADBLU INJECTOR, CONNECTOR AND
WIRING. CLEARED FAULTS, ROAD TESTED, OK
PARTS- QTY - - - FP - NUMBER- DESCRIPTION
1 7L0-973-702 HOUSING
1 GUS- 052-910-A3 UREA
1 000-979-174-EC SINGL. LEAD

2024-08-10 CUSTOMER STATES HE GETS A ADD BLUE FAULT NO RESTART 200 MILES. PLEASE CHECK AND ADVISE.
RAN GFF, STATIC FAULT FOR P20F4 AND WARNING ON CLUSTER. PERFORMED QUANTITY AND QUALITY TEST OF
ADBLU INJECTOR AND ADBLU FLUID. FLUID I S NEW AND INJECTOR IS PERFORMING CORRECTLY. INSPECTED ADBLU
TANKS AND FOUND TRANSFER PUMP ON PASSIVE TANK LOOKS VERY RUSTY. ATTEMPTED TO PERFORM AN OUTPUT
TEST AND PUMP DOES NOT FUNCTION. WITHOUT THIS PUMP THE ADBLU FROM THE PASSIVE TANK WILL NOT BE
TRANSFERRED TO THE ACTIVE TANK THEREFORE WILL NOT BE USED MAKING THE VEHICLE THINK IT IS OUT OF
ADBLU. MUST REPLACE PUMP AND REEVALUATE.
LOWERED ADBLU PASSIVE TANK AND REPLACED V436 TRANSFER PUMP. REINSTALLED TANK AND FILLED ADBLU
RESERVOIR AND RESET ADAPTATION. ROAD TESTED, ALL OK.

ADBLU WARNING ON DASH AND CHECK ENGINE LIGHT ON RAN GFF, STATIC FAULT FOR P20F4 AND WARNING ON
CLUSTER. PERFORMED QUANTITY AND QUALITY TEST OF ADBLU INJECTOR AND ADBLU FLUID. FLUID IS NEW AND
INJECTOR IS PERFORMING CORRECTLY. INSPECTED ADBLU TANKS AND FOUND TRANSFER PUMP ON PASSIVE
TANK LOOKS VERY RUSTY. ATTEMPTED TO PERFORM AN OUTPUT TEST AND PUMP DOES NOT FUNCTION.
WITHOUT THIS PUMP THE ADBLUE FROM THE PASSIVE TANK WILL NOT BE TRANSFERRED TO THE ACTIVE TANK
AND THEREFORE WILL NOT BE USED MAKING THE VEHICLE THINK IT IS OUT OF ADBLU. MUST REPLACE PUMP AND
REEVALUATE.
PARTS- QTY - - - FP - NUMBER- DESCRIPTION
1 4L0-131-901-C PUMP
2 GUS-052-910-A3 UREA
1 N-103-100-01 CLIP

2025-01-08 MAINTENANCE 'ADBLUE: FAULT! NO RESTART IN 150 MILES!' UP ON DASH; PLEASE CHEC
CK ENGINE LIGHT ON
CUSTOMER STATES CHECK ENGINE LIGHT IS ON

SUGGESTED SERVICES
ENGINE: CHECK ENGINE LIGHT
FAULTS FOR ADBLU SYSTEM PRESENT. FOUND CLOG AT INJECTOR. CLEANED AND THEN FILLED SYATEM TO
CLEAR FAULTS. AFTER ATTEMPTING TO ADAPT SYSTEM, ADAPTION WOULD NOT GO THROUGH. STARTED TAC
CASE 3350512 AND WAS ADVISED TO REPLACE REAR NOX SENSOR G687/1881 AND THEN PERFORM RESETS
FOLLOWED BY ROAD TEST AND MONITORING OF MEASURED VALUES. 2.00 DIAG 2.00 REPLACEMENT AND RESET

 

In reviewing the service notes/what got swapped out, I see typical Audi fault finding, which has ended up with almost everything on your reductant system getting replaced once, and some items (transfer pump, injector, NOx sensor 2, etc. getting extra love/attention. The interesting thing is them replacing the rear NOx sensor several times, but never did they replace the front NOx sensor from what I can see in the notes. Heck, they even replaced your friggin SCR catalyst, so you made out like a bandit. Lots of expensive parts.

What strikes me as really standing out is the corrosion/rust being noted and commented on so much by the techs, and this relates to the replacement of the CAT, the rear NOx sensor, the frozen bolts, etc, as well as the second replacement of the transfer pump, so I guess there must be an issue with corrosion where you live/drive. Do you ever take your Q7 to get an underbody wash performed during and post-Winter so that the road chemicals and/or salt brine solution doesn't attack/corrode everything under your car that's not aluminum? The roads where I'm at get salted down real good, so I wash my underbody and rinse out all my heat exchangers on front of car and rinse front of engine too; just as soon as the snow clears, etc.



BONUS!!!
I literally just found out that you can clean both NOx sensors (and the O2 sensors) with a very high success rate, basically 100%, if you can follow directions. O2 sensors are slightly lower as those have internal heater elements/electrical components that can fail outright.

Here's the link to the thread on Ross-Tech's help forum site; you'll need to read down to the cleaning info, but it's a good read for you:

https://forums.ross-tech.com/index.php?threads/5878/

 

Front Upstream NOx1 electronic interface


Front Upstream NOx1 sensor tip


Rear Downstream NOx2 sensor tip

I appreciate you sharing your expertise. Finally with a break from the rain I took up a DIY inspection and cleaning of NOx1 & 2. Where I’m stuck now is understanding the system programming, does it recheck each time, does it require clearing or system resetting. Idk.

I tried the battery disconnect for 30 seconds system reset but all that changed was additional messages including weak battery warning (not being driven, other than in and out of driveway), TPMS error (probably just need to check pressure and save settings), and the continued AdBlue Fault 150 miles No Restart.

Rear NOx2 already replaced twice. Front NOx1 probably the original 13yo 153k miles worn out sensor but finding too many NEW replacement sensors ranging from $80-$600. Found one for $125 with a 3yr warranty. Please advise.

 

Well, from your pics it's fairly easy to see exactly how nasty that NOx Sensor 1 looks comparted to the recently-ish replaced NOx Sensor 2 under the car.

I'd suggest you remove the NOx Sensor 1 from the car and clean it according to the directions linked prior in thread. A very well regarded, long-time contributor posted to the Ross-Tech forum on how to clean these sensors successfully...precisely so you won't need to replace the expensive buggers. That's up to you though.

You can also recognize the old sensor looks to be 'fouled', so check what's on it...oil? If you are game to forego cleaning it and simply buy a new one, then just pop the new NOx Sensor 1 in there, and that alone should resolve the issue once it is delivering correct data to the ECU/ECM module, etc., so long as the other sensors are functioning normally, which you can go into VCDS and select them to view cold (not started) as baseline to find outliers, etc., then agin when hot. The ECM and SCR system are monitoring all the O2, NOx sensors and EGT sensors closely.

These NOx sensors can be pretty costly unless you find a deal on one; just be 100% sure its the sensor for that position, and a 3yr warranty sounds great so long as the retail site/seller is one you can trust. I just found an EGT sensor on Rock Auto that I needed for my TDI as a closeout deal for $27, so definitely pays to look around...I was just about to pull the trigger and pay $95 for same sensor somewhere else, and $95 was the best price I'd seen up to that point, lol, Audi charges crazy mark-ups $$$ for these little sensors.