Mercedes Key Fob Not Working due to Faulty Antenna Amplifier

Mercedes Medic • 14 November 2019
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Today we worked on a 2004 Mercedes-Benz E-Class where the key fob remote did not work.

Problem

The key will only lock and unlock the doors if you were very close. The red light on the keyfob does turn on when you press the lock or unlock problem.

Solution

One possible cause is a blown fuse for the antenna amplifier, alarm.

If you replace the fuse for the antenna amplifier and it keep blowing the issue may be the antenna amplifier.

What you will need

  • Mercedes Antenna Amplifier

How to replace the antenna amplifier

On sedans such as E-Class and C-Class vehicles, the antenna amplifier is mounted on the C-pillar driver's dire. On SUV vehicles such as ML350 the antenna amplifier is mounted on the lift gate and requires the removal of the plastic trim from the lift gate.

Below are instructions on how to replace the antenna amplifier on a E-Class.

  1. Disconnect the battery.
  2. Open the rear door.
  3. Remove the weather strip form the door.weather strip door
  4. Remove the cover from the C-pillar. It is held in place with plastic trim. May require a little force to come out.location of mercedes antenna amplifier

    Picture of plastic retainer that holds this cover in place.

    b pillar cover retainer

  5. Locate the antenna amplifier. This is typically a green box mounted on the frame. It may also be black box.  It is on driver's side behind the rear windshield. If you have a SUV, it may mounted on the liftgate.mercedes antenna amplifier e class

     

  6. Unplug the electrical connectors from the antenna amplifier.Press and pull mercedes connector

     

  7. Remove the two 10mm nuts that secure the antenna amplifier to the frame.Mercedes antenna amplifier nut

     

  8. Remove the old antenna amplifier. Install the new antenna amplifier to the frame, tighten the 10mm nuts and reconnect all the wires.

Notes

  • Sometimes the issue is not the antenna amplifier itself, but the wires going to it that may have shorted.
  • When purchasing a replacement antenna amplifier we recommend buying a part with the same part number. You can also call the dealer and check if a newer part is avaliable.

Related Part Numbers

Here is a list of part numbers for various Mercedes-Benz antenna amplifiers.

  • 1708200389
    • 98-00 MERCEDES SLK230 ANTENNA AMPLIFIER
  • 2168200489
    • Antenna Amplifier Booster Mercedes CL600 CL63 CL65 C216 2007-13
  •  A 164 870 24 89
    •  GL550/GL450/GL350/GL320/ML550/ML350/ML320/ML500/
  • 2218208389
    • 2007-2009 MERCEDES S550 S-CLASS W221, ANTENNA AMPLIFIER

This is just a few part number for Mercedes-Benz antenna amplifier. Call your dealer or remove the old part to find the part number that will fit your car.