# How To: Audi TT Mk2 (8J) OEM DRL LED Replacement



## SwissJetPilot (Apr 27, 2014)

For anyone who has purchased the P21W LEDs to replace the OEM DRL bulbs, most have discovered that after installation, you'll get an error code. This will happen even with "CAN-bus compatible" LEDs due to the factory settings in the controller.

By changing your factory set-up, you can program the system to accept the LEDs. You simply change the vehicle light settings with an OBD devicel (e.g VCDS, OBDeleven, etc) install the P21W LED DRLs and you're good to go.

Before I changed the coding, I removed both the left and right OEM P21W DLRs and replaced them with the LEDs so they were already installed.

*NOTE* - The screens shown here are from my 2007 (Pre-Facelift) German spec Roadster. Yours may be different depending on the year and options.

*CAUTION - Before you make any code changes, it's best to run an AutoScan first and save (print) the file so you have a record of OEM factory code settings. Once you make a change and click "Do it!", there's no "undo". 

Update:* OBDeleven owners now have the LED retrofit capability with a new One-Touch feature located under* Apps* --> *Retrofits*. You can read about *here*.

With the VCDS program running, use the following window menus and settings:

1.) Select [09-Cent. Elect.]
2.) Select [Coding - 07]
3.) In the coding window, click [Long Coding Helper]
4.) From line 3) in the Long Code window, select Byte 21 and click on the drop-down menu
*Note - my default setting was "05 Bi-Xenon Front Light with separate Daytime Running Lights (DRL)" highlighted in blue*
5.) Select [06 Bi-Xenon Front Light with LED Daytime Running Lights (DLR)]
6.) Close the window with the red [X] in the top right corner
7.) In the Long Coding window, click [Do It!]
8.) Exit VCDS normally.

If you do it correctly, the system will accept the change and the LED DRLs will work perfectly!

With my TT, the DRLs are programmed to turn on the front parking lights (aka outside marker lights) - which I don't like. Within 09-Cent. Elect, click [Long coding Helper] and go to Byte 11 (Front Parking Light Dimming). Changed the value from Dec1: *0 *x 1 = 0 (0=100% bright) to Dec1: *1* x 1 = 1 (1=1% bright or about as dim as you can get). Unfortunately as you can see in the picture, the parking light is still barely on, but not completely off. :x

Note - The Byte setting values for lights seems to work like this: 1=as dim as it will go but is not completely off. Any value from 1-99 will make the light progressively brighter with each higher value, with 0 being 100% brightness. Simply enter the number, press [Enter], then go back to the Recode Module window and click [Do it!]. You'll get a message the code was accepted and the setting will be immediate. You can continue to run the VCDS program and change the setting "live" until you get what you want.
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## Vanu (Oct 2, 2016)

I've tried that before and it didn't work. The LED strip headlights have the blinker in the place of the drl led bulb and the led strip is in the place of the blinker. Not really sure what would happen when you try to signal, eventhough there might be no error on the DIS.


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## SwissJetPilot (Apr 27, 2014)

The VCDS screen shots and pictures are right off my set-up so I guess it will depend on the year and lighting configuration yours came with. Mine is a German-spec, late 2007 (pre-facelift) 3.2 Quattro Roadster. The P21W DRLs were stock OEM. There's no "strip LEDs" in these headlight assemblies, only what's shown in the illustration above.

I double checked all my lights; (e.g. parking lights, DRLs, blinkers, headlights, headlight hi-beams, fore and aft fogs and all the tail lights and LED third brake light) and they all work perfectly.


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## deextr (Sep 22, 2017)

SwissJetPilot said:


> For anyone who has purchased the P21W LEDs to replace the OEM DLRs bulbs, most have discovered that after installation, you'll get an error code. This will happen even with "CAN-bus compatible" LEDs due to the factory settings in the controller.
> 
> By changing your VCDS factory set-up, you can program the system to accept the LEDs. You simply change the vehicle light settings with a VCDS, install the P21W LED DLRs and you're good to go.
> 
> ...


Will this be the same if you have Bi-Xenon's with sequential indicators ? Or are they all the same? :?


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## SwissJetPilot (Apr 27, 2014)

I think the best way to find out if you can do this is through a VCDS scan to see what's available on your particular year and model. Remember that USA, UK and European models are set up differently.

One other note on the DLR set up, there are two options under 09-Cent.Elect DLR settings. From 09-Cent. Elect., select [Long Coding Helper] in the Recode Module. At Byte 0 you have the choice of either Daytime Running Lights Scandinavia or North America. With the Scandinavia option, all the exterior lights, except the headlights, are turned on. So this includes the tail lights and license plate lights.

For me, where tunnels are the norm in Switzerland and Northern Italy, this made the most sense since I don't have auto-light feature and it saves me having to switch my lights on to illuminate the rear end. What will happen through as I enter a tunnel, or when it starts to get dark, the instrument faces will dim out and only the needles will remain illuminated. I could re-code this, but it's a good visual clue that my headlights aren't on, especially in urban areas where sometimes it's hard to tell if your headlights are on because the streets are so brightly lit up.


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## deextr (Sep 22, 2017)

Buying DRL LED replacement bulbs seems to be an absolute minefield. Any recommendations? These are the best ones I could find.

https://www.ebay.co.uk/itm/2pcs-White-1 ... SwrIlaq587


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## SwissJetPilot (Apr 27, 2014)

I had very good luck with this company...

https://www.autobulbsdirect.co.uk/

I had to return the set of H6W's because they arrived broken. They didn't have any problems with returning them or providing a refund. Keep in mind these guys are just re-sellers, so they're buying the same Chinese LEDs as everyone else. But at least they provided good customer service which is always a dodgy issue with anything from eBay.

viewtopic.php?f=19&t=1623834&hilit=LED+SwissJetPilot

It's one reason if I can't find it locally or from a reputible re-seller, I buy directly from Amazon - but only where it's listed as "free shipping by Amazon". Dealing with third-party vendors is always risky especially with refunds from Chinese vendors.


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## deextr (Sep 22, 2017)

SwissJetPilot said:


> I had very good luck with this company...
> 
> https://www.autobulbsdirect.co.uk/
> 
> ...


Thanks for the link SJP. Will order from auto bulbs.


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## krish87 (Jan 14, 2017)

Thanks for the write up.

Did you or anyone manage to work out how to stop the sidelights coming on when the DRLs are on?
Mine didn't do this before but when I coded the LEDs in it started?

Also, I'm happy to take the sidelight bulbs out and code the error message out if it's possible?

Thanks


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## SwissJetPilot (Apr 27, 2014)

@ krish87 - Actually no, I couldn't get it completely off.

Not sure which one of these Byte options/setting would shut these off completely.

My next option is to pull the parking (sidelights) and paint the bulb black with some thermo-paint and put them back in. I figure at such a low setting, heating isn't an issue, it avoids a bulb fault on the DIS and best of all, no light out the front!

I've uploaded a PFD of the 09-Central Elect. modules and long coding helper window screen shots so you can browse through them without hooking up VCDS. If you figure out a way to shut down the parking lights, please let me know!!

View attachment VCDS 09-Cent Elect.doc.pdf

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## krish87 (Jan 14, 2017)

Thanks bud.

What if you deselect the cold diagnosis for the parking lights and pulled them out?

Would that turn off the DIS warning?


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## SwissJetPilot (Apr 27, 2014)

Hummm...that's a thought.


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## krish87 (Jan 14, 2017)

Let me know how you get on bud. 
The wife has well and truly embargoed me from "f*****g about with the car" (her words not mine) for a few days.

I prob won't get a chance to mess about with it until the weekend.

Other way I though would be to revert back to standard settings and disable the cold diagnosis on the DRLs.

Did yours always function like that before or only after you changed the coding?


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## Wolvez (Jun 22, 2018)

krish87 said:


> Thanks bud.
> 
> What if you deselect the cold diagnosis for the parking lights and pulled them out?
> 
> Would that turn off the DIS warning?


YES,

If Scandinavia DRL is selected, front and rear parking light will turn on with DRL. 
Put a check on Byte 17 bit 6 (parking light inactive)


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## Wolvez (Jun 22, 2018)

SwissJetPilot said:


> For me, where tunnels are the norm in Switzerland and Northern Italy, this made the most sense since I don't have auto-light feature and it saves me having to switch my lights on to illuminate the rear end. What will happen through as I enter a tunnel, or when it starts to get dark, the instrument faces will dim out and only the needles will remain illuminated. I could re-code this, but it's a good visual clue that my headlights aren't on, especially in urban areas where sometimes it's hard to tell if your headlights are on because the streets are so brightly lit up.


I have Auto-light, when entering a tunnel the headlights turns on but the instrument panel remains dim with needles illuminated. How to recode it?


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## SwissJetPilot (Apr 27, 2014)

Try under 17-Instruments, Coding-07, last group of options on the pop-up menu.


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## krish87 (Jan 14, 2017)

Fiddled with some settings including the inactive parking brake and they still came on.

The cold diagnosis isn't an option apparently as the car will still throw an error (not tried, just read up on it elsewhere).

My plan is to simply remove the bulb from the light but keep it in the holder and tuck it in the back of the lamp. 
This way the bulb is still connected, just not in the headlight if that make sense.


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## Wolvez (Jun 22, 2018)

SwissJetPilot said:


> Try under 17-Instruments, Coding-07, last group of options on the pop-up menu.


Thanks,



krish87 said:


> Fiddled with some settings including the inactive parking brake and they still came on.
> 
> The cold diagnosis isn't an option apparently as the car will still throw an error (not tried, just read up on it elsewhere).
> 
> ...


 Try changing the country on the instrument cluster.

After Unchecking cold diagnosis, make sure to clear the codes to remove all old error stored. No need to install the bulb.


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## krish87 (Jan 14, 2017)

I pulled the bulb from the light but kept it in the holder. Wrapped it insulation tape and slid it in to the back of the light.

Hopefully won't cause any issues.


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## krish87 (Jan 14, 2017)

Wolvez said:


> SwissJetPilot said:
> 
> 
> > Try under 17-Instruments, Coding-07, last group of options on the pop-up menu.
> ...


Does the unchecking cold diagnosis and pulling the bulb out definitely work?
I didn't do this as I read elsewhere it will still throw an error.

If it works, I'll give it a try tomorrow.


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## Wolvez (Jun 22, 2018)

99.9% SURE, before ordering the LEDs, I tested the coding while the headlight & taillight are unplugged. The computer detected the error before coding was done, if I will keep sending error on startup if I will not clear the faultcode stored.


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## Wolvez (Jun 22, 2018)

krish87 said:


> I pulled the bulb from the light but kept it in the holder. Wrapped it insulation tape and slid it in to the back of the light.
> 
> Hopefully won't cause any issues.


It could melt the plastic housing or wire insulation and burnout the bulb.

It's also possible to adjust that using any ELM327 & Carista app


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## krish87 (Jan 14, 2017)

Wolvez said:


> krish87 said:
> 
> 
> > I pulled the bulb from the light but kept it in the holder. Wrapped it insulation tape and slid it in to the back of the light.
> ...


You were right.... insulation tape = bad idea. It had started to melt. 
Tried all the configs. No luck. Error message kept coming back.

And I now need new side light bulbs as mine are covered in melted insulation tape.


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## Wolvez (Jun 22, 2018)

Make sure the coding is really accepted and saved if using a cloned cable. Also check if it can really clear the code by disconnecting and connecting the the MAF Sensor.


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## krish87 (Jan 14, 2017)

Wolvez said:


> Make sure the coding is really accepted and saved if using a cloned cable. Also check if it can really clear the code by disconnecting and connecting the the MAF Sensor.


It says coding accepted when I untick it and it lets me clear the fault code. 
As soon clear the faults. It comes back on almost instantly. 
It shows as unticked when I go back into it.


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## SwissJetPilot (Apr 27, 2014)

@ Krish87 - Have you tried going to into 09-Cent. Elect., Byte 17, and ticking the box for Bit 6 "Parking Light Function inactive (USA/Canada)? I haven't had time yet to test this on mine, but it would seem this should do the trick.


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## krish87 (Jan 14, 2017)

SwissJetPilot said:


> @ Krish87 - Have you tried going to into 09-Cent. Elect., Byte 17, and ticking the box for Bit 6 "Parking Light Function inactive (USA/Canada)? I haven't had time yet to test this on mine, but it would seem this should do the trick.


Hi mate. Tried this and it didn't work/do anything.


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## krish87 (Jan 14, 2017)

I would be happy to leave it but the parking lights are on full brightness when in DRL mode. 
They only dim to 1% when I turn the main lights on.

From what I have worked out. On the setting we have selected for LED DRLs. It treats the parking/side light as part of the DRL system and not as stand alone parking lights.

Annoying really as I was fine with the standard set up (no parking lights when DRLs on). I just wanted to change the DRLs to LED instead of halogen.


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## Wolvez (Jun 22, 2018)

krish87 said:


> I would be happy to leave it but the parking lights are on full brightness when in DRL mode.
> They only dim to 1% when I turn the main lights on.
> 
> From what I have worked out. On the setting we have selected for LED DRLs. It treats the parking/side light as part of the DRL system and not as stand alone parking lights.
> ...


Why not just disabled the DRL cold diagnosis instead? Much better to buy an error free LED for the DRL.


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## krish87 (Jan 14, 2017)

Wolvez said:


> krish87 said:
> 
> 
> > I would be happy to leave it but the parking lights are on full brightness when in DRL mode.
> ...


I couldn't find an option for this on mine.


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## Wolvez (Jun 22, 2018)

krish87 said:


> Wolvez said:
> 
> 
> > krish87 said:
> ...


Canbus Error Free LED is the best option.


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## tomasfuk (Oct 27, 2018)

Wolvez said:


> Canbus Error Free LED is the best option.


I don't think so. "CANbus Error Free LED" has some too small resistor in it, undersized, and it burns soon.

My solution is: Bi-Xenon with LED DRL coding, LED in parking light too (2 W power), with separate 220 Ω / 2 W resistor connected to the parking light LED in parallel. The resistor does not heat too much, max. 0,9 W dissipation. Parking (LED) light dimming coded to 25 %.


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## C50 (Jan 4, 2019)

Thanks, this worked for me so I'm running LED bulbs for my DRL. Annoyingly, I can't get the sidelights to bot come on with the DRLs too


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## Petar92 (Sep 29, 2019)

After so much trouble, I just made a full circle and came back to this post, as I can remember this being first thing I bookmarked, even before getting the car, and ever since trying to code the error out. I finaly did it, just like SwissJet Pilot stated in OP, and it works for me as well. LEDs bought on aliexpress.

Question: I have led bulbs I wanted to swich for brake lights, they fit and light up for a second when installed, then shut off and show an error. Did anyone do this retrofit and knows how I could get it to work without errors ? and WITHOUT resistors?

I have 2007 model, with 09 - Bordnetz Steuergerät H54

Thanks!!


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## SwissJetPilot (Apr 27, 2014)

LEDs generally won't work as a one-to-one replacement for incandescent bulbs because Audi (like most modern cars) uses Pulse Width Modulation (PWM). If you're unfamiliar with it, run a Google search or look for an explanation of PWM on YouTube.

Why Audi elected to make this a programmable option for only the DRL's is another one of Audi's design decision mysteries.

There are some out there, you'll just have to shop around.


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## tomasfuk (Oct 27, 2018)

Petar92 said:


> Question: I have led bulbs I wanted to swich for brake lights, they fit and light up for a second when installed, then shut off and show an error. Did anyone do this retrofit and knows how I could get it to work without errors ? and WITHOUT resistors?


https://www.ttforum.co.uk/forum/viewtop ... 9#p9248389


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## Hugorruss (May 22, 2021)

Hi,
Sorry to resurrect an old thread, but seems this is the best place to ask:

I've put in "CAN BUS error free" LEDs in the DRL spot on my 2007 Audi TT German spec car. I've done the coding suggested by SJP using OBDEleven dongle/software: 09 to turn on rear lights in byte 1, 26 in byte 21 to turn on Xenon with LED DRLs.

I keep getting these errors:


















02896 and 02898.

I've googled and can't find anything. Seems like the LEDs are defective? Or I'm not doing something right? Or I need a resistor even if I have can bus error free LEDs?

Thanks in advance for any help!


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## SwissJetPilot (Apr 27, 2014)

As shown below, with VCDS the option for LED DRL is under a drop-down menu. Looking at my OBDeleven, it doesn't look like this feature is present. Have you tried using the Adaptation feature? FYI - I tried to check just now looking on my Smartphone (images below), but Adaptations won't work off-line so you'd have to hook it up to your car and check.

*VCDS Drop-Down Menu*









*OBDeleven --> Central Electrics -->Byte 21 & Central Electrics - Adaptation*


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## SwissJetPilot (Apr 27, 2014)

I checked the *Apps* feature, but it doesn't seem to be there either. I've sent an email to the OBDeleven team to explain this issue and to ask if they can add this to their One Touch App features.


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## Hugorruss (May 22, 2021)

Wow, first off thanks for such a quick reply 

Hmm, OK I will check the adaptations. Yes, OBDEleven doesn't have the nice UI for coding the LEDs, but in byte 21 I have "26" hex value the same like you do. I set byte 0 to 09 hex value as well and that did turn on the rear lights. I started with the exact same values as you (I think we have pretty much the exact same car/year/spec/etc) and only made these two changes at first. Then I tried to uncheck the "cold diagnosis for parking lights" but that didn't make the errors go away.

I think in your VCDS screenshot the red arrow is pointing at the wrong byte, isn't it?


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## SwissJetPilot (Apr 27, 2014)

@ *Hugoruss* - Good catch on the byte error. Thanks! I fixed it. 

Here you can see both versions side by side. For OBDeleven it's called "East Europa" and VCDS calls it "Scandinavia". In both cases, it turns on the rear lights when the front DRLs are on. IMHO it should be the default DLR setting. Not having the rear lights on with the front DRLs, especially through all these tunnels in Swissyland, makes no sense.


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## SwissJetPilot (Apr 27, 2014)

OBDeleven just released a new App --> Retrofit for the LED DRL Bulb Swap. You can read about it *here*.


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## Hugorruss (May 22, 2021)

SwissJetPilot said:


> @ *Hugoruss* - Good catch on the byte error. Thanks! I fixed it.
> 
> Here you can see both versions side by side. For OBDeleven it's called "East Europa" and VCDS calls it "Scandinavia". In both cases, it turns on the rear lights when the front DRLs are on. IMHO it should be the default DLR setting. Not having the rear lights on with the front DRLs, especially through all these tunnels in Swissyland, makes no sense.
> View attachment 481143


Hey I know this is late but better late than never. So I had set the DRL to LED mode and then I was still getting the parking light errors. I tried every setting I could think of to just disable the error but I couldn't get it to work so I was just living with the error as everything else seemed fine.

Then I saw your post about the app so I figured I'd give it a try. Long story short: I guess the LEDs I bought already have resistors, because I used the app to turn OFF LED mode, and now I don't get the error at all.

I guess I had missed to try it without the LED DRL setting, and thinking back I made the LED setting and put in the LEDs all in one go so I never actually tried it in "regular bulb" mode 

Thanks for all the help, great forum!


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