MB Medic Mercedes-Benz Repair Guides, Service, How To DIY
Last updated:
Learn how to replace the rear taillight bulbs on a Mercedes-Benz C-Class W203.
This guide covers the 2001 to 2007 C-Class W203: C230, C240, C280, C320 and C55 AMG. Check the bulb type for your model year before ordering parts.
Replace the failed bulb to clear the Lamp Defective warning in the instrument cluster. Use the specified bulb type and wattage. Some LED replacements can trigger a bulb warning or flicker if they are not compatible with the W203 bulb monitoring system.
Bulbs you can replace from inside the trunk:
- Brake and stop light: P21W
- Turn signal: PY21W
- Reverse light: P21W
- Tail, parking and standing light: R5W 5007
Step by Step: How to Replace the Rear Tail Light Bulbs
- Turn off your lights. Allow the lamp and bulb to cool before handling them. Install a 12 volt bulb of the same type and wattage as the original.
- Open the trunk.
- Locate the taillight assembly with the burned-out or defective bulb. Fold the trim over.
- Rotate the plastic locking tab 90 degrees to the vertical position.
- Optional: Disconnect the wiring connector.
- Remove the bulb assembly.
- Locate the defective light bulb. Use the photo below to identify the failed bulb.
- Press the bulb gently into the socket, turn it counterclockwise, and remove it.
- Press the new bulb into the socket and turn it clockwise until it locks in place.
- If you unplugged the wiring connector, push it back on until it clicks. Then push the bulb assembly back into place and lock it with the twist tab you turned earlier.
- Push the trim cover back in place.
- Before you shut the trunk, switch the ignition on and check every lamp you disturbed: brake, turn signal, reverse and parking. The Lamp Defective message clears once the monitoring system sees the new bulb drawing current. If the brake lights still do not come on with a good bulb fitted, the next thing to suspect is the brake light switch.
Video: How to Replace the Tail Light Bulbs
Before you buy parts, scan every control module, not just the engine. It shows the root fault behind the warning lights and tells you whether the problem is still active. See how to do a full health check.
