Just bought a 2001 TT convert and like it a lot. I understand there have been issues with the xenon lights, especially the left or driver side not working or working intermittently. My research has led me to the conclusion that the issue is USUALLY with the xenon lamp ignitor which is unfortunately an integral part of the headlight assembly and not easily replaced. Have checked out both ballasts and in my case it appears to be the ignitor. Solutions range from cheap aftermarket ballast and ignitor replacements but this requires some modification. More expensive solution is to purchase aftermarket but good quality headlight assembly replacements (Hella) and replace the whole assembly which while less expensive seems to be overkill. The third and unproven and to my knowledge undefined is to replace the assembly with a halogen assembly, substantially less expensive however not sure if this will work, i.e. will the computer need adjustments to the soft coding so that there is not a fault noted and in fact can you move down the evolutionary trail and go to halogen from the more sophisticated xenon. Sleepless north of Seattle!

 

Well I actually have had this issue not once but twice. The first time was actually the passenger side and all I did was go on ebay and ordered a new ignitor. I paid 60 bucks. Now how do you install it? Well lol I just unplugged the old one and very carefully set the new one in the housing making sure it wouldnt hinder the auto level. Then just put the cover back on. Maybe it wasnt pretty but who looks at the inside of your headlight anyway haha. The second time I had to take the lens off the drivers side anyway so I replaced it at the same time with the lens off. Hope this helps as other than that your looking a much more expensive fix.