Home / DIYs / B7 Audi A4/S4/RS4 Independent Fog Light Mod



Ever wanted to be able to turn your fog lights on independently of your headlights? After owning a B7 for over 6 years and getting countless questions about this, I’ve finally gotten around to doing this “5 minute” mod and it’s pretty slick, actually.


The modification is written up pretty well in the following link: Audizine DIY, so I’ll just expand upon some pointers and tips to make it easier, but essentially you just pop out the headlight switch and then use some copper wire to connect two of the prongs, then cover the old prong with electric tape. Lastly, update VAG-COM to rest of the world and you’re good to go!

Here is the rest of my pointers and notes:

  1. Firstly, some people have asked if this can be done with the VAG-COM only, i.e. no connecting of wires or messing with the headlight switch harness – the answer is a definite no, unless you have a very early (02-03?) B6 model, then it might be possible by just changing your VAG-COM to Canadian Settings. Anyone with a B7 will need to connect the prongs in the headlight switch, and most B6 owners will need to as well…
  2. While I still strongly recommend an authentic Ross-Tech VAG-COM cable and VCDS software, this can be done with a knock-off cable according to other commenters on Audizine. For specifics on how to program this via VAG-COM, check out this link where it says “Independent Fogs.” Your coding should be either 01011 for halogen headlights or 01021 for xenons with DRL.
  3. Wrapping the two prongs together is a little more difficult than you’d think, and whoever did the write-up has excellent craftmanship – mine is much uglier looking, but functional all the same. Use a flat head screwdriver to help guide and wrap the wire around the two prongs, as well as hold the electric tape in place.
  4. This mod will allow you to turn the fogs on when the headlight switch is in parking light mode by pulling the switch outward. Your Parking/City Lights will still be on, so it’s a good idea to put LEDs in there so it looks nicer as my DIY demonstrates.
  5. This mod is also compatible with my HID Fog DIY, so check that out, too…


All in all, it took me about 20 minutes, but mostly because I was taking my time. After testing it in my garage, it’s a nice mod and I like that I can choose when I want my fogs on or off, originally I thought this mod would turn the fogs on whenever the parking/city lights were on and that would be annoying. This is a great mod, and I’m not sure why Audi wouldn’t offer this from the factory – but thanks to PSYC0TIC ONE on Audizine for writing up a way to do this ourselves!

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About the author: Nick Roshon


Nick has been an Audi owner and fanatic for the last 10 years, and started Nick's Car Blog in 2009 to share DIYs and pictures of his A4. Currently he drives a 2012 Audi TT-RS, and has previously owned a B7 S4, B7 A4, and an 82 Audi Coupe (GT) LeMons race car. In his day job, Nick is a digital marketer and lives in San Diego, CA, USA.


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  1. I think this option is only suitable for US cars… we in europe can already use fog lights independent of the headlights.

  2. Will the fog lights stay on with the high beams?

  3. Only if you want them to, just pull out the headlight knob like normal.

  4. I have done this mod to my car and the only difference is that I can have the fog lights on with the running light. If I change to high beam, my fogs still shut off. I did not make any vag-com changes so I’m not sure if that’s why or not

  5. How to make working daytime running lights with Fog Light? =)

  6. No way to do this that I’m aware of, wasn’t able to find anything by searching on Audizine either.

  7. Hi Nick first this blog is awesome I have a question this mod can be done with out the vag-com software

  8. Not to my knowledge, Grover…but you can make it work with a cheapo $30 cable from eBay, if you’re trying to do this without spending a lot of money…

  9. Can you let me know what cable it is

  10. I don’t know Grover, I have an authentic ROSS-Tech cable. I’m assuming any of the knock-offs on eBay are likely to work, but if you plan on keeping your car a long time I’d recommend getting an authentic cable for finding a friend or shop that has one that you can use.

  11. Hey just wondering what you were using for fog light bulbs?

  12. Hi Brandon – I bought these HID fog lights: http://nickscarblog.com/cars/hid-fog-lights-on-a-b7-audi-a4-and-s4 and then have yellow lamin-x over them.

  13. article is very much informative.thank you

  14. I’m new to the Audi world , always been a fan though , got the girl an 07 a4 and I’m learning along the way , I’m wanting to do the fog mod but what’s the vag-com deal ? What happens if I do the mod without it ?

  15. I’m not sure it will work without the coding, it basically changes the car to work as if it is in Europe where they have independent fogs rather than US where that isn’t an option. The Vag-Com cable is just an OBDII cable that lets you interface with the car’s software and reprogram things to unlock features/options in other countries or models.

  16. Where did you get the grille I’m just wondering if I can get one the same as that for my A4

  17. Definitely Justin. Is your A4 an S-line or regular A4? If S-line you can get the same exact ones, if just an A4 there is a replica RS4-style grille you can get that is much cheaper then do the same thing for the lower grilles.

    RS4 Grille Write-up: http://nickscarblog.com/reviews/audi-rs4-grille-installed-pics-info
    Lower Grille Write-up: http://nickscarblog.com/reviews/rs4-grille-lower-grilles-installed-plus-other-goodies

  18. My car is just an a4 non s-line I wouldn’t mind a honey comb grille withe a carbon fibre filler plate but it’s just an idea. Also what front lip do you have would it work on the non s-line a4? I have been looking at the CUPRA r carbon fibre lip. Not sure if that’s what’s on this car or not 🙂

  19. Did you get pre cut circles for the lamin-x on your fogs? Do you have a link.

  20. Yeah, they are pre-cut…SUPER easy to install! Link and write-up here: http://nickscarblog.com/reviews/yellow-lamin-x-on-a-b7-audi-s4

  21. The honeycomb grille is way cheaper for the non-sline since they make replica ones, I think they’re about $100 last I checked and look really good. The Cupra Lip looks great on a non-sline, Votex also makes a lip / bumper extensions that looks pretty good as well! I have the Kerscher front lip: http://nickscarblog.com/reviews/kerscher-front-lip – also check out the Deval front lip.

  22. What version of Vag-Com did you have to use?

  23. I use a genuine Ross-Tech Vag-Com cable (USB) with the latest software they provide.

  24. Hey I really liked your blog! I do have a question tho! My right light seems to flicker and turn off more often. But I’ve noticed that it does it only while in motion. Then of course I turn off and off the switch and both my lights work but only for a short period of time. Sometimes I get lucky and they work the full time. For some strange reason when my left light flickers my dog lights do it as well

  25. Sounds like either a bulb or ballast is going bad, or you have a loose connection. Try switching the bulbs and seeing if the problem switches sides – if so, time to replace the bulbs.

  26. Just to clarify, when the my HID’s come on when set to auto, is there a way of also having the fogs come on as well? or does this mod only work with the city lights?

  27. Unfortunately, I’m not aware of any way to do that (fog lights come on with Auto), Zac.

  28. Hey nick. Ever since I did the coding for this mod, my DRLs no longer turn on. I don’t have the led ones either, its the regular type of bulbs. I’ve tried all combination of light settings from inside the car but no matter the conditions they just stay off. Any help would be very appreciated. Thank you.

  29. Hi Mike – what is your exact coding in Central Electornics, and do you have xenons or halogens? The second to last digit controls the DRLs – it looks like the Audizine DIY says it should be either 01011 (Halogen) or 01031 (Xenon) but that would actually disable DRL for xenon – so I would do 01021 for xenons, because the second to last digit being a 2 is for Bi-Xenon Headlights WITH Daytime Running lights, whereas the 3 is for Bi-Xenons WITHOUT DRLs. Reference this picture specifically: http://www.bimmerboard.com/members/clumpymold/original/Resize%20of%20DSC04559.JPG

  30. Thanks nick. I have the OEM xenon headlights like you have. I will check the codes when I get back home.

  31. Thanks Nick, problem solved.

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