I’ve been asked how I did this conversion on my B7 Audi A4 in the past, so I’m finally getting around to writing it up in typical Nick’s Car Blog fashion to share with inquiring minds. It’s a great mod and while I won’t attempt to recreate step-by-step instructions, I’ll go into deep detail as to what you need, why you’ d want to do this mod, and where to find instructions once you’ve accumulated all of the parts…Above you can see my former A4 before and after the conversion, with the picture on top featuring the OEM bi-xenon headlight housings.

OEM Xenons versus Aftermarket Kits

The biggest consideration that you need to determine first is do you want to go the OEM route, or do you want to consider aftermarket options? It will probably suprise no one that has read this blog here that I highly recommend the OEM route, but it’s at least worth mentioning your other options. The only downside to the OEM route is that it is the most expensive option, but in terms of functionality, output and aesthetics, it’s you’re best option. Here are your primary options:

OEM Bi-Xenon Headlight Housings, Ballasts & Bulbs


The highest quality option, and one that will look great and work great for years to come. They also will help improve resale value of your car, and after the conversion it will be nearly impossible for anyone to tell your car ever had halogens in the first place. Pictured above are my OEM bi-xenons I retrofitted to my A4, which were E-Codes I sourced from Germany.

Aftermarket Headlight Housings, Ballasts & Bulbs


This is probably your second best option, because the aftermarket headlight housings have projectors to focus the xenon beams so that you’re not blinding oncoming traffic, as opposed to drop-in kits. The downside is that the options out there, primarily manufactured by Depo, are of lesser quality and are immediately recognizable as aftermarket. Many of the options include LED running lights to look more like the modern style Audis (B8 models or R8s, to be more specific) but often come out looking a little cheap and also tend to have problems with the LEDs burning out.

Drop-In HID Kits

HIDs with or without a Projector

The advantage of this route is that you’ll only spend about $50 for the HID “kit” that includes ballasts and bulbs, but the downside is that your headlight housings lack projectors so the HID lights will be blinding to everyone in sight. I’ve done this in the past and although you can definitely see better while driving, it looks pretty terrible to everyone around you and doesn’t really belong on an expensive German car. I recommend this route for the fog lights as they’re positioned low enough on the car not to bother anyone, but I do not recommend this for your driving lights as it’s a safety issue. For a good read on what a projector is and what it does, check out this thread on Reddit – which also deserves photo credit for the image above.

Retrofitting projectors to your halogen housings, then using a drop-in HID kit

This has been done before, but it takes extreme DIY savvy to do. Audizine headlight expert “fly300kts” has retrofitted Acura and Subaru projectors into halogen housings, and it actually creates an even higher quality cut-off than the OEM Audi projectors do, but this is a very technical and tedious DIY that isn’t for the faint of heart – and if you do it wrong, could end up falling apart. If you’re brave and savvy, this could be a legitimate option for you, but won’t be for most…

OEM Conversion: What You Need to Buy (And How Much It Costs)

OEM Bi-Xenons

Okay let’s assume at this point you would like to go the OEM route – what’s it going to set you back? The OEM headlights are insanely expensive when purchased through a dealership – expect to pay $900-1200 per side, and that doesn’t even include the ballasts and misc. parts you’ll need. No thanks! Instead, you’re best method here is finding lightly used headlights on eBay or the Audizine classifieds and retrofitting to your car – they can be found quite easily off of wrecked cars in sets or singles, and be had for much cheaper. In general, expect to pay between $500-800 for a complete set of OEM bi-xenon headlights with bulbs and ballasts depending on condition and how eager the seller is. Check out these eBay listings for a good start, then cruise over to the Audizine Classifieds to see if any sets are available.

 Pic  Title  Details
2006-2008 Audi A4 S4 RS4 B7 OEM Xenon Headlight HID Ballast Control Unit Module Current Price: $135.0
# of Bids: 0
Ending: 20 days 17 hrs 33 mins
Audi A4 S4 RS4 B7 Xenon Headlights OEM Head Lamps 2006-2008 Left + Right PAIR Current Price: $478.5
# of Bids: 0
Ending: 22 days 14 hrs 6 mins
Audi A4 S4 RS4 B7 Headlight RIGHT OEM Head Lamp Xenon 2006-2008 Current Price: $254.5
# of Bids: 0
Ending: 6 days 11 hrs 26 mins
# of Bids: 0
Ending: 4 days 8 hrs 15 mins
AUDI A4 B7 2006-2008 BI Xenon Headlighs Front Lamps Left + Right OEM Current Price: $849.95
# of Bids: 0
Ending: 7 days 11 hrs 36 mins
 View all items... (Powered by: WP eBay Ads)  

Note that there are a few options when selecting a set of OEM bi-xenon headlights:

  1. US versus European Market headlights – these differ in that they have chrome inserts rather than dull grey, and often also have clear turn signal lenses rather than amber (although some markets in the EU still use amber, so amber does not necessarily mean they are US spec). 
  2. With or Without AFS – AFS stands for automatic leveling & focusing system, and is the feature where the projectors dynamically adjust and turn when your car turns to illuminate the road ahead of curves and maneuvers. It’s a great feature, but not necessary if all you want is HID lighting. Note: Auto-leveling and AFS are two different things. Auto-leveling is equipped on all xenon lights, and only controls up/down leveling. AFS is adaptive and goes left/right and is more sophisticated than simply auto-leveling, so do not assume these are the same thing.

OEM Xenon Headlight Part Numbers:

  • US with AFS: 8E0941029BD (L) and 8E0941030BD (R)
  • US w/o AFS:  8E0941029BA (L) and 8E0941030BA (R)
  • EU with AFS: 8E0941029BP (L) and 8E09410030BP (R)
  • EU w/o AFS: 8E0941029BM (L) and 8E0941030BM (R)

Secondly, you’ll need an adapter harness. Kufatec makes a great harness that is literally plug-and-play for all of your needs. This will make sure the new headlight housings get the right amount of power for the ballasts. It is not necessary to replace anything else, such as the headlight switch, for this mod. This harness costs slightly over $100 and can be found on the Kufatec website.

Lastly, this is a good time to change out any of the other bulbs you want, such as adding LED DRLs and City Lights, Clear Turn Lenses, or other lighting related mods. Since the headlights will be off your car, this is by far the easiest time to install lights and resistors. You can also black out your headlight housings, if that’s your thing. This is also a good time to install a RS4 grille, since your bumper will be coming off anyway.

All in all, expect to pay around $800 for the headlights and wiring adapter, give or take about $100…

Installing OEM Xenons on Halogen Equipped Cars

Okay so you’ve got all of the parts, and your headlights are ready to get installed – now what? Here comes the fun part…

Step 1 – Remove the bumper and headlights

This is the “easy” part, more or less…and something you’ll need to get used to when owning a B7, as it’s required for a lot of things. Follow this guide: http://www.audizine.com/forum/showthread.php/234131-B7-A4-S4-Clear-Corner-Mod-Removal-of-Bumper 

Step 2 – Install New Headlights & Wiring adapter

This part is pretty tedious, as you have to snake the wiring adapter through the firewall and into the cockpit, then splice it into your headlight knob in the interior…this isn’t technically challenging, just a little tedious. There are two guides to do this – on my A4 I followed the Audiworld one, but the Audizine one was written more recently and is very detailed. I’d suggest reading both…

Step 3 – Use VAG-COM To Update Settings

Last but not least, you have to update your car’s computer so it knows you have xenons and not halogens anymore. This is a simple coding change, but requires using a VAG-COM cable so you’ll either need to buy one, borrow one, or find a shop nearby that will do this for you. Once you have access to a cable, it should only take 5 minutes to change. To adjust follow these instructions (and always write down your original settings first, just in case):

Go to Components – Module 9 and change the fourth digit to either a 2 (with Daytime Running Lights) or a 3 (without DRL). For example if the code reads xxx?x, update the ? to a 2 or 3 (it is likely a 0 or 1 currently, which are for halogen cars). Additional documentation on VAG-COM coding of headlights can be found on the Rosstech website.

In Summary:


I definitely recommend going the OEM route if you’re looking to add HIDs to your halogen equipped A4 or S4. Expect to spend between $600-1000 to get a complete set of headlights and the wiring adapter, which is somewhat pricey, but remember it will improve the resale value of your car…not to mention the safety benefits. The installation requires removing the bumper, installing the wiring adapter, and updating your ECU via VAG-com, but is certainly DIYable. Many have done this in the past (myself included) and can help walk you through it if you run into issues. Expect to spend 2-3 hours completing this mod depending on how experienced you are with removing the bumper.

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