2002 Audi TT 8N - No fault lights, Low-speed ABS Engagement - explainable faults in autoscan

[kozmo659]

Long story, but I'll keep it brief...
The front hubs were replaced along with wheel bearings earlier this year to correct bearing wear. Aftermarket hubs with bolt-on tone rings were used in the repair (the shop has been removed from future consideration). Subsequently, the low-speed ABS engagement issue started - under 10 mph the abs kicks on. ABS functions normal in sudden stops over 10 mph. I pursued the issue and discovered the LF tone ring bolts had backed-out and sensor had been damaged from rubbing. I've cleaned-up and trued the tone ring, and replaced both front wheel speed sensors. Along the way, I purchased VCDS to help with diagnosis, which brings me to my question... Should I replace the ABS controller, or replace the hubs again, and which should I do next? (OEM Tone rings can't be removed from the hubs, and the hubs must be removed to replace the aftermarket versions).

I ran an Autoscan this morning. it shows wheel sensor faults which were set as I worked through the truing of the front tone rings with the car raised and freewheeling. I believe those are red-herrings, but didn't want to clear faults just yet. Thanks in advance for the help.

No Code Provided

Monday,28,September,2026,11:08:27:36004
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 11 x64
VCDS Version: 26.9.0.3 (x64)  HEX-V2 CB: 0.4713.5
Data version: 20260828 DS378.0
www.Ross-Tech.com


VIN: TRUWT28N621029275   License Plate: RR5T81
Mileage: 150172   Repair Order: 092826-01



--------------------------------------------------------------------------------
--------------------------------------------------------------------------------


Chassis Type: 8N (8N - Audi TT (1999 > 2007))
Scan: 01 02 03 08 15 17 22 35 37 45 55 56 76 77
 
VIN: TRUWT28N621029275 
-------------------------------------------------------------------------------
Address 01: Engine        Labels: 06A-906-032-AMU.lbl
   Part No: 8N0 906 018 AN
   Component: 1.8L R4/5VT     G   0004
   Coding: 06710
   Shop #: WSC 01236
   VCID: 7DA01836C4E9A4A28C6-5160
   TRUWT28N621029275     AUZ5Z0B3245183

2 Faults Found:
18010 - Power Supply Terminal 30
            P1602 - 35-10 - Voltage too Low - Intermittent
16486 - Mass Air Flow Sensor (G70)
            P0102 - 35-10 - Signal too Low - Intermittent
Readiness: 0000 0000

-------------------------------------------------------------------------------
Address 03: ABS Brakes        Labels: 8N0-907-379-MK60-A.lbl
   Part No: 8N0 907 379 H
   Component: ESP ALLRAD MK60     0101
   Coding: 0022544
   Shop #: WSC 01236 785 00200
   VCID: 41D8A4C6FD910042A8E-5160

2 Faults Found:
00287 - ABS Wheel Speed Sensor; Rear Right (G44)
            003 - Mechanical Failure - Intermittent
00285 - ABS Wheel Speed Sensor; Front Right (G45)
            003 - Mechanical Failure - Intermittent

-------------------------------------------------------------------------------
Address 08: Auto HVAC        Labels: 8N0-820-043.lbl
   Part No: 8N0 820 043 A
   Component: TT-KLIMAVOLLAUTOMAT D03
   Coding: 00140
   Shop #: WSC 01236
   VCID: 280E19627BEBD10A8F0-258E

1 Fault Found:
00604 - Potentiometer Positioning Motor for Air Flow Flap (G113)
            30-10 - Open or Short to Plus - Intermittent

-------------------------------------------------------------------------------
Address 15: Airbags        Labels: 8N0-959-655.lbl
   Part No: 8N0 959 655 A
   Component: Airbag Front+Seite 5000
   Coding: 01103
   Shop #: WSC 01236
   VCID: 3E22DF3A896F7FBAD5C-5160

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments        Labels: 8Nx-920-xxx-17.lbl
   Part No: 8N1 920 980
   Component: KOMBI+WEGFAHRS. M73 D14
   Coding: 07244
   Shop #: WSC 05146
   VCID: 73B43E0EF2ADE2D2EA2-4B1E
   TRUWT28N621029275     AUZ5Z0B3245183

4 Faults Found:
00849 - S-contact at Ignition/Starter Switch (D)
            30-10 - Open or Short to Plus - Intermittent
00779 - Outside Air Temp Sensor (G17)
            30-00 - Open or Short to Plus
01304 - Radio
            49-00 - No Communications
01305 - Databus for Infotainment
            37-00 - Faulty

-------------------------------------------------------------------------------
Address 22: AWD        Labels: 02D-900-554.lbl
   Part No: 02D 900 554 C
   Component: HALDEX LSC  ECC     0010
   VCID: 201E014213DB294AC70-4B1E

No fault code found.

-------------------------------------------------------------------------------
Address 35: Centr. Locks        Labels:. 8Nx-962-267.clb
   Part No: 8N8 962 267 A
   Component: Central Lock/Alarm  D06
   Coding: 15884
   Shop #: WSC 05146
   VCID: 3FDCA23E8E6576B2DEA-4F26

4 Faults Found:
01374 - Alarm triggered by Terminal 15
            35-00 - -
01616 - Signal Wire to Interior Monitor
            36-00 - Open Circuit
00956 - Key 2
            09-10 - Adaptation Limit Surpassed - Intermittent
00849 - S-contact at Ignition/Starter Switch (D)
            31-00 - Open or Short to Ground

-------------------------------------------------------------------------------
Address 55: Headlight Range        Labels: 4B0-907-357-AUT.lbl
   Part No: 4B0 907 357
   Component: LEUCHTWEITEREGLER  D004
   Coding: 00010
   Shop #: WSC 01236
   VCID: 659050564C790C62746-51AC

No fault code found.

End----(Elapsed Time: 02:52, VBatt start/end: 11.2V/11.1V. VIgn 11.2V)-----
------------------------------13 Faults Found------------------------------

 

[nugentp]

Long story short, I know for fact the ABS unit on the 8N TT is very sensitive to differences in the signal strengths from the wheel speed sensors. Even at low speeds it can detect anomalies. You probably need an oscilloscope to compare the signals - impossible to evaluate them any other way and throwing new sensors at every corner gets expensive and tedious.

 

[kozmo659]

@nugentp - Thanks for the reply. I'm of the mind it's going to be the tone rings themselves, even more tedious and expensive! Thanks again!

 

[Ziddywerks]

I will disagree with the above statement. I would recommend logging wheel speed signals and posting the results here, vcds is more than capable of logging those signals. Also to make a long story short if the tone ring was loose and damaged it should be replaced end of story. Common sense dictates if you had issues and found a part that was compromised, dicking around with it to make it true and straight is just asking for a problem, it's something that can cost you time and aggravation looking for a problem that you found on your initial inspection that you thought you" fixed".

 

[Crasher]

I have seen aftermarket sensors where the air gap is too much. Also, were the correct Pr:G97 front hubs used, part number 8N0 407 613 C? These are obsolete genuine and not widely available aftermarket.

 

[Jef]

Aftermarket hubs with bolt-on tone rings were used in the repair

Are these Chinese Replacement Auto Parts? I would always want to go with OE stuff. Now anything with an electrical connector on it, I suggest to get from the dealer. But mechanical bits and bobs, such as wheel bearings, as long as they are legit OE stuff, I don't think it really matters where you buy them from.

 

[Ziddywerks]

Are these Chinese Replacement Auto Parts? I would always want to go with OE stuff. Now anything with an electrical connector on it, I suggest to get from the dealer. But mechanical bits and bobs, such as wheel bearings, as long as they are legit OE stuff, I don't think it really matters where you buy them from.

I think the issue is that many of such parts for such an old vehicle was discontinued.

 

[Vdub]

TT 8N does have known problems with faulty ABS-module-electronics.

 

[Crasher]

I would check the air gap

Video disabled

This video is disabled because third-party cookies are not currently accepted. To view YouTube videos, please accept third-party cookies.

Accept third-party cookies

 

[Ziddywerks]

TT 8N does have known problems with faulty ABS-module-electronics.

What audi doesn't? All of them did from that era, hell the new ones have issues too , once it started if never stopped. Bosch 5.0, 5.3,5.7 were notorious for failure as were the ATE units as well and still are on some models.

 

[Crasher]

The only ones we have seen a lot of failure on is the 2010 ish Mk60.

 

[Vdub]

Passat 3B/3BG, Audi A4/6 1996-2005 were also equipped with bad ABS-units

 

[Crasher]

Yes, we had a few of those Bosch units fail.

 

[Ziddywerks]

Passat 3B/3BG, Audi A4/6 1996-2005 were also equipped with bad ABS-units

Passat, A4, A6, TT and anything mk4 golf or jetta they all had issue even the q7 and touareg units are known problems. This is nothing new.

 

[Crasher]

I have seen several Q7 and Touareg pumps fail due the the vacuum sensor failing but I didn't put it down to be the units to blame.

 

[Ziddywerks]

I have seen several Q7 and Touareg pumps fail due the the vacuum sensor failing but I didn't put it down to be the units to blame.

Those care had the best location for that pump and control unit. Maybe in Englang it was elsewhere but in USA it was in the cowling on the passenger side(right side) of the car. Such a great spot to get covered in debris and water. Also having said that those vehicles had issues with the cowl drains getting clogged with leaves and other debris mostly due to owner negligence because of this abs unit were constantly subject to water and other debris just sitting there, ecm were and issue as well for the same reasons.

 

[Crasher]

That your poor passenger has to endure siting in the left seat, I find disquieting but one must surmise this being the price one has to pay for chucking a delivery of tea into the drink over a mere question of crown taxation…