A complete guide to reset your Mercedes car key ?

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Daily use of our vehicle leads to the wear and tear of multiple components that interact during operation, including our access key and/or ignition key. Among the many reasons that can cause a problem in this device, the most recurrent is the malfunction due to the discharge of the internal battery of the key. To continue with its proper functioning this element must be replaced. Note: This malfunction can occur when changing the battery of our car.

But what happens when the key battery has been replaced and we notice that any single command works properly when the buttons are pressed. We might think that our key has stopped working completely but sometimes this specific situation can be fixed only by resetting the device. This situation applies to all car brands without exception, and to illustrate this point, let us talk about the case of the German premium brand Mercedes-Benz. Below you will find the correct procedure to reset and reconfigure your key with your vehicle.

Table of Content

  1. How do I reset my Mercedes-Benz fob key?
  2. Conclusion

1. How do I reset my Mercedes-Benz fob key?

As a preliminary step, it is necessary to validate the operation of our key and that it emits the corresponding signal when pressing some of the buttons (lock, unlock, panic, and/or trunk). Initially, it can be checked by pressing any button and seeing a small red LED illuminated very close to the panic button. Then you will need to use your mobile phone’s camera. The infrared signal emitter is located at the top of the key housing, initiates the camera app on your phone, and places it in a position parallel to the flat surface of the key. When any button is pressed, a flash of light shall be displayed. If the light signal is not displayed on the camera or on the key casing, it is very likely that there will be a malfunction with the device.

Step 1

The initial step is to synchronize the key on your Mercedes Benz. It is necessary to place the key on the ignition switch for a few seconds while the vehicle is switched off. Without turning the key, you will need to press the “lock” button.

Step 2

Remove the ignition switch key without releasing the “lock” button for 10 seconds.

Step 3

After 10 seconds and without releasing the “lock” button, press the “unlock” button 5 times in a row.

Step 4

Stop pressing the “lock” and “unlock” buttons. Press the “box” button only once.

After completing the 4 steps of this procedure, review the correct functioning of your key by pressing any button and validating that the vehicle has performed the function. For model specific instruction check your owner’s manual.

In some cases, this problem may persist after performing the key reset procedure. This will require a more detailed inspection of the remote key system.

We can start with a basic visual inspection of the electrical system and verify the condition of the electrical relays and fuses within the system are optimal. Vehicles with multiple security, infotainment, and comfort systems such as Mercedes-Benz have multiple fuse boxes around the vehicle. In the case of the remote key system (Antenna Amplifier), it is possible to find the fuse in charge of its operation, at the rear of the driver’s side. To access this fuse box, it will be necessary to open the trunk, remove the cover, open the cover of the fuse box, locate the fuse, remove it with the help of a special tool and verify that it has no visible damage.

If the fuse shows some damage, it will be necessary to replace the electrical component. It is very important to follow this recommendation otherwise if there is any change in the circuit parameters, it may trigger major problems in the vehicle’s electrical system.

The key reset procedure described above will need to be performed once more to verify that all components are working correctly.

If the problem continues after completing all these steps, a module diagnosis will be required. For this point, it will be necessary to use a scanner and a specialized program that will allow us to obtain the fault code of the module. It is recommended to consult your trusted specialist for a detailed analysis of the failure, as well as a suitable solution for this problem.

2. Conclusion

It is important to clarify that this procedure only applies when key resetting is required due to any of the causes seen above. If there is a problem with the hardware of the device where it is not possible to request it and you need to replace it with a new key, it is recommended to contact your authorized Mercedes-Benz dealer as this is the only way to request a replacement key to guarantee your safety and that of your vehicle.