6R Aftermarket LED Conversion Incompletely Coded

[nugentp]

I could use some help from any 6R/PQ25 platform experts with an aftermarket LED lighting conversion that was carried out without coding changes (not by me). I gather this should be handled by BYTE 18 of the BCM coding byte but there is a special note in VCDS software indicating that no guidance is provided on the value of these bits. I have tried to disable the lamp diagnosis for the lamps in the other documented bytes but the error for the brake lamps persists - presumably as the BCM does not know they are LED.

Recent Auto-Scan provided for context. Everything is OE, except the powertrain and brakes. Aftermarket LEDs front & rear were added and there is a full MFSW as well.

Tuesday,05,May,2026,20:31:37:30756
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64
VCDS Version: 26.3.0.0 (x64)  HEX-NET CB: 0.4701.4
Data version: 20260320 DS375.1
www.Ross-Tech.com


VIN: TRUZZZ8N841028314   License Plate: 6R32


Chassis Type: 8N-VW25 (6N0)
Scan: 01 03 04 08 09 15 17 19 25 44

VIN: TRUZZZ8N841028314   Mileage: 204640km-127157miles

01-Engine -- Status: OK 0000
03-ABS Brakes -- Status: OK 0000
04-Steering Angle -- Status: OK 0000
08-Auto HVAC -- Status: Malfunction 0010
09-Cent. Elect. -- Status: Malfunction 0010
15-Airbags -- Status: OK 0000
17-Instruments -- Status: OK 0000
19-CAN Gateway -- Status: OK 0000
25-Immobilizer -- Status: OK 0000
44-Steering Assist -- Status: OK 0000
-------------------------------------------------------------------------------
Address 01: Engine        Labels: 022-906-032-BDB.lbl
   Part No SW: 022 906 032 FA    HW: 021 203
   Component: MOTRONIC ME7.1.1G   5903
   Coding: 0000032
   Shop #: WSC 87119 806 641192
   VCID: 4FEE7790DFA508E70A-5184
   VINID: 92296AAAA21E2040400880C110E20D3EB3

No fault code found.
Readiness: 0010 0100

-------------------------------------------------------------------------------
Address 03: ABS Brakes (J104)       Labels:. 6R0-907-37x-ESP82.clb
   Part No SW: 6R0 907 379 BE    HW: 6R0 907 379 AF
   Component: ESP8.2i front H05 0001
   Revision: --------  
   Coding: 230248E3436D00B9C42912E2C2D400821300
   Shop #: WSC 00788 648 00255
   VCID: 02488EA49977358FD5-8056

No fault code found.

-------------------------------------------------------------------------------
Address 04: Steering Angle (G085)       Labels:* 6R0-959-654.clb
   Part No SW: 6R0 959 654     HW: 6R0 959 654
   Component: LENKW.SENSOR  H06 0060
   Serial number: 090465LJ5000ZR
   Coding: 01
   Shop #: WSC 00000 000 00000
   ASAM Dataset: EV_LWSKLOVW25X 005001
   ROD: EV_LWSKLOVW25X.rod
   VCID: 7EB0FA54E18F516FB1-802A

No fault code found.

-------------------------------------------------------------------------------
Address 08: Auto HVAC (J301)       Labels: 6R0-820-045-9AB.clb
   Part No SW: 6R0 820 045 N    HW: 6R0 820 045 N
   Component: Man AC        H02 0202
   Revision: 0003SH02  
   VCID: 393A2948B021B657C4-806C

1 Fault Found:
00819 - High Pressure Sensor (G65)
            009 - Open or Short to Ground
             Freeze Frame:
                    Fault Status: 01101001
                    Fault Priority: 2
                    Fault Frequency: 1
                    Reset counter: 249
                    Mileage: 204641 km
                    Time Indication: 0
                    Date: 2020.09.25.
                    Time: 20:27:18

             Freeze Frame:
                    Temperature: 9.0°C
                    Hex Value: 0xFFFF
                    Hex Value: 0xFFFF
                    Voltage: 14.30 V
                    Absolute Pres.: 0.0 bar
                    Time: 0.00 s


-------------------------------------------------------------------------------
Address 09: Cent. Elect. (J519)       Labels:. 6R0-937-08x-09.clb
   Part No SW: 6R0 937 087 K    HW: 6R0 937 087
   Component: BCM PQ25 H+4  H46 0254
   Revision: BF046001    Serial number: 0434 266121636
   Coding: 25B029B808A1060001280EC02DAB0ED8B08041FF60060000200000000000
   Shop #: WSC 12469 483 00190
   VCID: 45C255B8CCD9C2B7B0-8010

   Subsystem 1 - Part No: 1K0 955 559 AH  Labels: 1K0-955-559-AG.CLB
   Component: RLS 210912 05  54  0403
   Coding: 03302D

   Subsystem 2 - Part No SW: 6R0 959 802 AB    HW: 6R0 959 802 AB  Labels: 6R0-959-802.CLB
   Component: J386__TSG_FT  008 1621
   Serial number: KU0KU020091200018422
   Coding: 18BC30

   Subsystem 3 - Part No SW: 6R0 959 801 AD    HW: 6R0 959 801 AD  Labels: 6R0-959-801.CLB
   Component: J387__TSG_BT  008 1621
   Serial number: KU0KU017091200010077
   Coding: 18BC30

   Subsystem 4 - Part No SW: 6C0 959 442 C    HW: 6C0 959 442 C
   Component: E221__MFL-DC1  H04 0103
   Serial number: 29160000565620056125
   Coding: B0FFFF

1 Fault Found:
01758 - Bulbs for Brake Lamps
            011 - Open Circuit
             Freeze Frame:
                    Fault Status: 01101011
                    Fault Priority: 2
                    Fault Frequency: 1
                    Reset counter: 249
                    Mileage: 204641 km
                    Time Indication: 0
                    Date: 2020.09.25.
                    Time: 20:27:50


-------------------------------------------------------------------------------
Address 15: Airbags (J234)       Labels:| 5K0-959-655.clb
   Part No SW: 6R0 959 655 K    HW: 6R0 959 655 K
   Component: VW10Airbag01X H10 0020
   Revision: --------    Serial number: 003GX01EFA8E Dataset Number: v00307236R0 0001
   Coding: 003158
   Shop #: WSC 01383 785 00200
   ASAM Dataset: EV_AirbaVW10BPAVW250 A01001
   ROD: EV_AirbaVW10BPAVW250.rod
   VCID: 4AD86684EDC72DCF5D-801E

   Crash sensor for side airbag: driver side:
   Serial number: 3575HRB40511KADSGHBT

   Crash sensor for side airbag: passenger side:
   Serial number: 3585HRB404T1KADSF0UF

   Crash sensor for side airbag: driver side rear:
   Serial number: 3515RRB405H1GLOM6HSP

   Crash sensor for side airbag: passenger side rear:
   Serial number: 3525RRB401C4UHC45H7L

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments (J285)       Labels:| 5K0-920-xxx-17.clb-SRI1
   Part No SW: 6R0 920 960 D    HW: 6R0 920 960 D
   Component: KOMBI         H03 0207
   Serial number: 00000000000000
   Coding: 440E00
   Shop #: WSC 31414 790 50316
   ASAM Dataset: EV_Kombi_UDS_VDD_RM09 A04052
   ROD: EV_Kombi_UDS_VDD_RM09_004_VW23.rod
   VCID: 36202274893F592F29-8062

No fault code found.

-------------------------------------------------------------------------------
Address 19: CAN Gateway (J533)       Labels:. 6N0-909-901-6R.clb
   Part No SW: 6N0 909 901     HW: 6R0 937 087
   Component: GW-K-CAN TP20 H46 0254
   Revision: BF046001  
   Coding: 002100
   Shop #: WSC 12469 483 00190
   VCID: 70ACD46CA3DB371F33-8024

No fault code found.

-------------------------------------------------------------------------------
Address 25: Immobilizer
Cannot be reached

-------------------------------------------------------------------------------
Address 44: Steering Assist        Labels: 6Q0-423-156.clb
   Part No: 6R0 423 156 C
   Component: LenkhilfeTRW        V278
   Coding: 11230
   Shop #: WSC 00788
   VCID: 302C146CF75B771F73-8064

No fault code found.

End----------(Elapsed Time: 01:21, VBatt start/end: 14.3V/14.2V)-----------
------------------------------2 Faults Found-------------------------------

Current BCM coding = 25B029B808A1060001280EC02DAB0ED8B08041FF60060000200000000000
Byte 18 = 0x41
Byte 19 = 0xFF

I dug out a very old scan from the car when it had the factory fitted regular lights and Byte 18 was also 0x41 so I think that is the problem as the BCM is expecting non LED lamps. Other bytes were of course different as we since added an OE MFSW and made some other changes along the way, but for the record the 'factory fresh' BCM coding with the legacy lights etc is below:
Original BCM Coding = 24B029BF08A10000012808002D2B0ED00000410F60060000200000000000
Byte 18 = 0x41
Byte 19 = 0x0F

I was unable to find any trustworthy guides online for Byte 18 coding on the specific PQ25 BCM (6R0 937 087 K) which I gather should be capable of the necessary changes, but I am definitely not a 6R platform expert so I could use some pointers as I gather that bad coding changes can be permanent - or maybe that is just some internet FUD which is significant enough to make me want to check.

 

[nugentp]

Errr maybe I can only achieve this on a higher spec BCM with 089 hardware ?

 

[MasterTommy]

If this is indeed a BCM using byte 18 to select a lighting configuration, then I wouldn't try too hard to try to find a 'correct' value to set for byte 18 since there likely isn't one.

I only played around with PQ25 lighting configurations a few times, but from what I observed;

Byte 18 is used to select a 'preset' lighting configuration. Since you have aftermarket lights, I would probably assume that there is no preset for these lights available that would 100% correctly configure the BCM for your lights. What you will likely need to do is download one of those PQ25 BCM EEPROM configuration tools of which there are a few freely available, to directly change the BCM lighting parameters. You will probably also need to get a cheap universal OBD cable. With such a tool you can configure the individual BCM lighting output to an extent that is not achievable by just switching lighting configurations using byte 18 values.

 

[nugentp]

Interesting - I thought such low level pokery was the domain of higher end tools like VCP. I also don't know if the current 087 BCM variant has the HW ability to cater for all the different light combinations... my latest research on the subject points towards 089 or 090 for that.

 

[Crasher]

What you are doing is illegal in the UK, a road traffic offence, will invalidate your insurance and is an MOT failure. Any way, the VIN is for a 2004 3.2 V6 quattro TT.

 

[nugentp]

My signature gives a clue to the source of the VIN on that car - I haven't put the 6R VIN into the R32 ECU yet. Car has passed UK MOT multiple times on those LED lamps without any issues so maybe try scaremongering someone else.

 

[nugentp]

For more clarity - these are aftermarket lights specifically designed for LED bulbs - they are not LED bulbs placed into optics designed for halogen bulbs.

 

[Crasher]

Have you fitted a self levelling system and headlight pressure wash? Have you told your insurance company about the modification?

 

[nugentp]

All mods declared. Thanks for your concern on this matter.

 

[TTT]

Now publish vin

 

[nugentp]

The car is street legal with everything declared to insurance - relax y'all.
I was just trying to see if there was a way to clear this annoying fault code when the car is scanned.

 

[iichel]

I'm afraid that's the best you'll get it with a 6R bcm

 

[nugentp]

What about the likes of higher spec BCM listed against 6R Polo and Ibiza - 7H0 937 089 F - does that feature the kind of flexibility needed to properly disable the nag errors for rear LEDs ?