Mercedes-Benz HID Xenon Headlight Bulb Replacement

Learn how to change the Mercedes HID Xenon headlight bulb yourself. This guide applies to 2005 and newer Mercedes models, including E, C, S, CLS, G, GL, ML, and R Classes. How do you know if the Xenon bulb is why your Mercedes headlight is out? Typically a Xenon HID bulb will get dimmer, and the light color may change to pink near the end of its life. If you notice these symptoms, then replace the HID Xenon bulb. It is recommended to replace both bulbs simultaneously for two reasons. HID bulbs have a certain lifespan measured in hours. This means the other bulb will most likely fail soon. Second, the light color will not match your stock headlight bulb.

Procedure

1. Turn off the ignition and ensure the lights are turned off.
2. Wait 10 minutes. This will allow any residual voltage to discharge. HID bulbs operate at a voltage that is thousands of volts when the bulb ignites. Such high voltage can cause injuries or shock.
3. Access the back of the headlight. Remove the back cover by unclipping it. If you have a round cap, remove it by twisting it counterclockwise.
4. Unplug the wire from the ignitor.
5. Remove the ignitor/ballast by twisting counterclockwise and pulling it away. Note that on some models, such as S-Class, this will also remove the bulb. The bulb will remain in the headlight on other models, such as the R-Class (R350/R500). Follow the next step to remove this bulb.
6. Press and squeeze the two tabs of the metal wire and unlock. Remove the HID bulb from the Mercedes headlight.

Installation

1. Place the HID bulb in the headlight. Make sure it is sitting properly and is pressed all the way. The HID bulbs have a couple of channels that need to line up properly in the headlight assembly. If the bulb came out with the ignitor, then install the bulb on the ignitor instead.
2. Lock the bulb into the headlight.
3. Install the ignitor by placing it on the bulb and locking it in place. First, you need to line up the four tabs.
4. . Twist the bulb clockwise to lock it.
5. Connect the electrical wire by pressing it in the ignitor. Reinstall the cap, and you are done.

Troubleshooting Mercedes-Benz HID light problems

Check the fuses first. Each headlight has its fuse on a Mercedes-Benz. If no headlight fuse is present, then they are controlled by a SAM module. If the fuse has not blown, the next thing you need to check is the ballast. One way to check is to swap the ballast from the passenger to the driver’s side. If the problem is moved to the other headlight, the problem is the ballast. Also, check the connections to the headlight for corrosion. It is not uncommon for the water to get to it and corrode the terminal. In rare cases, the wires inside the headlight assembly may also get damaged or melt. Keep in mind that while a burned Mercedes HID Xenon bulb is the most common reason why your Mercedes-Benz headlight is out, there can be other issues as well, including:

• Faulty HID Ballast
• Ignotor
• Blown headlight fuse.
• Corroded headlight terminal
• Defective SAM Module
• Loose connection

I replaced the Xenon bulb on my Mercedes, but the light is still not working. What else could it be?

• Faulty HID Ballast
• Bad ignitor when applicable
• Blown headlight fuse. Each headlight has its fuse.
• Corroded headlight terminal
• Defective SAM Module
• Loose connection

My headlight works fine, and then it goes out. Replaced the bulb several times already. What could be the problem?

Make sure you are using the correct HID bulb. Don’t use cheap HID bulbs. The ballast or igniter may also be defective. If the same bulb goes out and turns back on, the problem is not the bulb. It is usually the ballast or igniter or a SAM module.

Mercedes HID headlight flickers or flashes; why?

At the end of its life, an HID bulb may flicker, change color and appear weak. Generally, if flickering is happening with OEM equipment, the problem is the ballast or the igniter. Not the bulb. If you are upgrading to HID lights, there isn’t enough power going to the ballast. In day running light mode, less power is delivered to the headlight. While at night full 35 watts are delivered to the headlight, and the headlight works fine.

Check these troubleshooting and repair guides for more help on your Mercedes-Benz.

Frequently Asked Questions

How do I know if my Mercedes xenon bulb or ballast is bad?

A bulb usually dims, turns pink or flickers before failing. If a new bulb does not fix it, or the light does not come on at all, the ballast or igniter is the likely cause. Swapping bulbs side to side helps confirm.

Should I replace both xenon bulbs?

Yes. They age at the same rate, and a new bulb next to an old one will look a different color.

Can I touch the HID bulb glass?

Avoid it. Wear gloves, and wipe the glass with alcohol if you touch it, since oils can shorten bulb life.

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