How I Swapped My E46 BMW’s Burned Xenon Headlights
Certain E46s are more prone to failure than others.
Drivers typically don’t pay their headlights any mind until a bulb burns out, and most cars only ever need regular bulb replacement. That's not the case with an E46's xenons. Nope, in a classic stroke of Bavarian brilliance, the xenon bulbs of some projector-equipped cars physically burn the plastic reflector of the headlight. This drastically reduces light output and eventually renders them completely useless. During my tenure as a 2004 BMW 330i ZHP owner, I encountered and set out to fix this exact issue.
Here’s the deal: A fair amount of these cars suffer from this problem but not all of them. Two suppliers made xenon headlights for BMW: Bosch AL and ZKW. Bosch headlights don’t burn out. ZKW sets, however, are very prone to burning out and cause truly terrible visibility at night.
You can easily tell the two headlights apart by looking at the units. ZKW headlights have a clear-looking projector, while Bosch AL versions have a line that bisects the projector. If all else fails, drive your car at night. If you can’t see, you likely have ZKW headlights.
This issue used to be a bit tougher to fix because you couldn’t just order new parts from ZKW and you would have to spend exorbitant money on all new light assemblies. Back in the day, people would manually retrofit universal projectors into their headlights with some basic hardware, a Dremel, and a lot of patience. I’ve done a retrofit into a halogen headlight and its much more straightforward than making a different projector fit where a factory one is supposed to go. Lucky for me, it’s much simpler these days.
My go-to source for high-quality lighting stuff is The Retrofit Source (TRS), and no, the company didn’t pay me to say that. Generally, TRS offers a quality product for decent prices, and it has a premade E46 projector repair kit that I ordered for this repair for about $250. It replaces the garbage ZKW stuff with a Morimoto D2S 5.0 projector, some Morimoto HID bulbs, and comes with brackets to quickly and easily fit the new projector into the headlight, with only minor drilling required.
I started on a Thursday afternoon, already familiar with this from my previous white ZHP I owned in 2016. Removing the headlights from the car is simple: Unclip the rubber seal around the light, remove the beauty panels beneath the lights then unscrew three six-mm bolts that secure the headlight to the car. One is behind the headlights close to the middle, and two are on top of the headlights. Then get a Phillips screwdriver and unscrew the corner lights using the small access hole on the fender. Unplug about five connectors and the headlight should come out easily.
Unlike most headlights, the facelift E46 sedan stuff isn’t sealed with a high-strength butyl glue or permaseal. You can simply unhook the plastic lens from the rest of the housing with a screwdriver and get immediate access to the headlight, which saves a lot of time and mess. Some other variations of E46 may be different. Be gentle with the black aesthetic bit in the headlight, it's very prone to breaking and I had to repair mine, but it’s basically inevitable that stuff will break on an aging E46.
After that, I removed the rear panels for the xenon bulb and the halogen flash-to-pass lights. Now we had to free the reflector and projector assembly from the light housing, which is done relatively easily with a strong index finger and a pick. Looking in from the open rear panel for the xenon bulbs, look toward the middle of the light and upward. You should find a circular piece of shiny plastic with two tabs that click into the black headlight housing. Use the pick to free one tab, use your finger to free the other, then push the headlight out with some force. There is a ball at the bottom of the headlight for the self leveling mechanism that needs to pop out.
Once you fight a bit, it’ll pop out and you’ll probably drop it. If it didn’t break, everything is fine. Now we get to the meat of the install with replacing the projectors.
It's easy enough at this point, though negotiating the drilling seems intimidating. It was simple with my method of using the provided projector brackets as a template for drilling. I could install two of the provided screws with spacers, and use a small drill bit to drill a pilot hole for the other two screws. In my case, I decided to only drill one hole and use three bolts per side due to difficulty drilling the last hole, which is still plenty of support for the projector.
Once that is squared away, I terminated the high-beam solenoids to the provided end so I could retain bi-xenon functionality, a simple enough cut and crimp job. Then there was the question of mounting the projector shrouds onto the new projectors, which I did with JB quik weld. I let the shrouds cure for a little while before I re-assembled everything to make sure that all of the wiring harnesses were in their right place.
At this point, it’s basically done. Close the headlights back up, put them on the car, and marvel at the newfound light output. I’ve wanted to try the Morimoto D2S 5.0s since I had the Mini H1s on my old Civic Si, and I’m not disappointed. The light output is clear, insanely bright, and the cutoff is razor sharp with some nice blue lens effect for some style. Because the E46 has automatic leveling headlights, all I had to do was level them at a nearby wall about 25 feet away from the car so I never worry about blinding other folks.
That, my friends, is all you need to do. I’m in love with how good the headlights are, and they are easily the best headlights I have in my family’s entire fleet of new and used cars. Next time, I’m going to have to tackle the terrible headlights of my mom’s 2015 Jetta TDI and that will be more useful as a complete retrofit guide.
For now, I urge any of you E46 owners out there to fix those ZKW headlights. Onwards.
Got a tip or question for the author? You can reach him here: firstname.lastname@example.org
MORE TO READ
How I Used Coding To Defeat My VW GTI’s Stability Control Systems
Modern stability control is talented but it can often get in the way of fun.
How Roll Center Affects Your Car’s Dynamics
Before you lower your car in the name of cornering, learn what roll center is.