Started having issues on my 09 Gti with xenon headlights. Troubleshooting this system can be an expensive nightmare. Some tips
* Remove the headlights to change the bulbs. It’s tempting to try to do it in the car but it’s really easy to break retainer rings and seat the bulb crooked and arc out your ignitor. It just gets more expensive from there and it’s really not hard to remove the grill and front bumper. If you can turn a wrench and at least a third of your brain works properly you won’t have an issue. I’ve done it both ways and have broken 100% more parts doing it with the headlight in the car.
if one headlight stops working, swap bulbs. If it still doesn’t work, swap ignitors. If the latter works you have a bad ignitor. If it still refuses to work with a good known bulb and a good known ignitor, check out the ballast.
If you have to change a bulb, change both at the same time. The cost of hid bulbs – click this site – may give you a minor heart attack, but resist the urge to buy the really cheap ones. Youll be doing it all over again in a year.
Buy a set of bulb retainers. Just in case. If you break one you can’t install the bulb until you get a replacement. Amazon sells the retainer if you do a quick search.
If you use contact cleaner on the plug for the ballast be sure to use sparingly and keep the headlight lens facing up. Failure to do this will let contact cleaner drip down into the inside of the headlight and melt a nice hazy spot on your newly repaired headlight.
* Rain, or the automated car wash tends to get the connector for the ballast wet. Corrosion causes the light to flicker on and off. Don’t let this problem go as it’s really hard on the bulbs.
I installed this ballast and it resolved a long standing issue with my driver side headlight not working. Shipping was fast and pricing was very good for this type of part. I couldn’t be happier. Now I’ll probably hit a deer.