Based on the popularity of my LED Interior Lighting post, and by popular request in the comments section, I decided to write another guide for LED License plate bulbs on a B7 Audi A4, S4 and RS4. They definitely look awesome, and are a relatively cheap mod at ~$30 total. Best of all, installation takes merely a few minutes and all that is required is a small screwdriver in most cases.
The trouble with this mod is that the with some B7 models (any A4, S4 or RS4 from 2005.5-2008), the installation of these bulbs sometimes causes a Light Out error. Personally, I installed mine and never had any problems with a bulb out error message or flickering issues, and I’ve talked to countless others who have never had problems either, but there are more than a handful of examples of those who have posted on Audizine who did encounter problems.
There are many theories as to which models or trim packages throw the Bulb Out error and which don’t, but from everything I’ve read, it’s mostly just luck of the draw/random. Many believe that if you have the multi-color information display in your gauge cluster (the LCD screen between your speedometer and RPMs) you are more likely to have an bulb out warning message, although Bulb Out errors do occur for the non-color version (those with only red colored pixels only).
Regardless, here are my recommendations – IMO it’s worth trying your luck as you can always revert back to the OEM halogen bulbs if you get a bulb out message, learn to ignore the bulb out message in your gauge cluster, or install an extra resistor to avoid this (more on this below). A few others have reported flickering issues with LED license plate bulbs, which can also be fixed using resistors.
For bulbs, look for a 39mm Festoon bulb that has a BUILT IN RESISTOR, or plan on purchasing your own resistor or load balancer to eliminate any issues. The built-in resistor is critical, as it will greatly reduce the chances of a bulb out message. The two options I’ve seen with the best reviews and success rates are
Option 1 - Buy “Error Free” LED License plate bulbs. Note they are not always error free for B6/B7 Audis due to our electrical systems, although they are less likely to cause errors than the typical 39mm Festoon bulb:
- 42 Draft Designs – this is what I’ve been using for ~2 years without problems. They say on their site not to use these bulbs for a B7 A4, but that’s just so they’re not liable to accept returns in the case you get a bulb out error – essentially, you must assume all risk they might not work or work but product codes.
- TunerDomes – their bulbs also include built-in resistors to help prevent error codes. I haven’t tried these personally but know a few people who run them. Like the 42 Draft Designs bulbs, a lot of people are running these successfully without any codes or errors, but a few here and there have reported error codes or flickering – again, it’s really kind of luck of the draw….(read a review here on Audizine from user Quattro)
Bulb Installation: lift up your trunk lid, remove your license plate for a little extra wiggle room, then remove the two screws holding the light cover in. You’ll probably need a specialty screwdriver like the ones used on eyeglasses as its a very small screw. Then pull out the old bulbs and snap in the new bulbs. Be sure to test it before re-installing the light covers, just to make sure the bulbs are making contact (you may need to bend the contact points of the base) as well as to see if you get any bulb out errors first.
Resistor Installation: if you need to install resistors, you’ll need to remove the liner of your trunk to access the wires. There are two screws that come out using a Phillips screwdriver, pictured below. One is below the trunk release handle and the second one is in a similar location on the opposite side of the trunk. Once the screws are removed, then there are four clips on the top edge and four clips on the bottom edge which will release when you firmly tug near each clip.
Once the trunk liner is pushed to the side, install the resistor. You’ll want to tap the brown wire and the purplish-gray wires that are furthest to the left of the harness. I found easiest to remove the harness to install the resistor first.
I find it works best to strip part of the brown wire and gray/purple wire first so the resistor makes good contact, as I find the red-plastic splicers don’t always cut all the way through. It doesn’t matter which wire you attach to which, just make sure the resistor bridges the brown wire and gray/purple one. Warning: the resistor gets VERY hot VERY quickly so don’t touch it once you’ve turned the lights on. I mounted the resistor using 3M double sided tape and then plugged back in the harness and turned the car on to test that the lights still turn on and no error warnings – success! If you still get a warning, go back and check our connections and make sure the exposed wires are lined up correctly within the red plastic splicer.
Disclaimer: I’m not responsible if you buy any bulbs and they don’t work, nor any damage you may cause to your car while working on it. Any modifications you perform on your vehicle are done at your own risk. That being said, there isn’t too much of a risk of causing any damage here, except you may be out the cost of LED bulbs in the event they flicker or cause a bulb out message.
Similar Posts:
- B7 Audi A4, S4 and RS4 LED Daytime Running Lights (DRL)
- Audi A4 Brake Light Replacement
- HID Fog Lights on a B7 Audi A4 and S4
- B7 Audi Clear Corner Mod
- How to Install B6 S4 Recaro Seats into a B7 A4 with No Airbag Warning Light
Hi,
Quick question, you said to look for a 39mm bulb and meanwhile the 42 Draft Designs link connects to a 42mm bulb. Which size will work in the b7? I just ordered to 42mm and then saw that you said 39mm
Yeah you’ll want 39mm bulbs. I must have linked to the wrong product, I’ll update that now. I’m really sorry about that – hopefully you can return them before trying to install – 39mm is kind of a tight fit so there is a good chance 42mm will be too big. Really sorry dude…
No worries man! Thank a lot! Your blog is sick and your car is looking fresh
Thanks Matt! Really appreciate it
Hi Nick,
The one on your car (pictured on the page), is it the blue or white led? I would like to mimic that of the lexus color.
Thanks
Those are the white, believe it or not. I think they used to call it “Cool White” but now it’s just listed as white. Hope that helps and be sure to let me know how it goes and what you think of the color….
Hi Nick,
I got the led’s for the license plate. They look great, but unfortunately, the light error message came up. I looked at the website to add the extra resistor, but that seems like alot of work. Any other ideas? can this be fixed via vag-com?
Thanks,
JR
Nothing in VAG COM to help unfortunately – you’re only options are the resistor or just live with the light out warning…wish that wasn’t the case
[...] car over your average A4. Exterior Mods:- Halogen to Bi-Xenon Conversion- Fly’s v4 LEDs- LED License Plate Lights- Cupra Lip- B7 S4 Mirrors- Black side markers- Black/chrome plate filler- 15% Rear tint, 35% Front [...]
42 Draft High Intensity 39mm in Cool White have been sold out for some time. Cool White in the regular 39mm are sold out as well, would these work though just in case they come in before the High Intensity? Any other suggestions beside the two mentioned above?
Thanks!
Really any 39mm LED with a built-in resistor should work, I think there are several other brands that make them – look for something that is supposed to be Error Free or has a CAN-BUS installed. Something like this might work nice: http://store.ijdmtoy.com/Audi-A4-Error-Free-LED-License-Plate-Lights-p/led_01_sku29.htm
I bought a pair of 39mm from 42 Draft Designs, the built-in resistor does not work?
what should i do? Is there any brand out there is workable?
Thx!
It doesn’t work as in the bulb doesn’t come on at all? Or it doesnt work in the sense of the LED turns on but you get a bulb-out warning. If the former, return the bulb, its probably defective. If the latter, you’ll need to install a load balancer or extra resistor.
it is working, but the LEDs are flickering & have bulb-out warning too.
I guess I have the mutli-colored Dash (red & orange).
thx for reply; it is a nice blog.
Hey Nick,
I’ve tried a few different brands of 39mm led bulbs but none seem to work. I heard it could be due to having a navi system? I was wondering if the 42 Draft Design bulbs have built on resistors. I have a ’06 audi a4 non s-line with navi package (multi-color display). Any help would be great!!
When you say they don’t work, what do you mean by that? Do they flicker, do they cause a bulb out error, or do they not light up at all? The cars equipped with Navi and color DIS (driver infomation system, the screen in between your speedo & tach) tend to have a harder time with the LED license plate bulbs for whatever reason, but I know it can be done as my buddy Blake has them on his RS4 with navi + color DIS, he just had to add an extra load balancer to get the bulb out error to disappear.
It lights up, but with any bulbs i’ve tried the error message comes up. Ima try and put a the load balancer and see if that works.. Thanks again!!
I know this is an old post, but I was wondering if you Nick, or anyone else had trouble removing the damn license plate screws. I bought the the bulbs over a year ago but i gave up on the initial install because i couldn’t get the light cover off and started stripping the screw. Frustrating but i have no other ideas and i left the halogen bulb as is for the time being. I read in different places people strip the screws and end up replacing the whole license light housing, which i am trying to avoid.
thanks in advance
I remember them being tough too. I went to the hardware store and picked up a set of smaller screwdrivers intended for eyeglasses and such, and then just used a lot of force to hold the screwdriver down while I twisted. In my opinion its easier to unscrew them with the trunk halfway open – consider getting a buddy to hold the trunk in that position while you use the screwdriver.
If it does strip, you could probably drill out the screw, then just replace the screw itself. I don’t see why you’d need to replace the whole housing for that…