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mercedes stop start not working

Mercedes Start/Stop Not Working

There may come a day that the Start/Stop function on your Mercedes-Benz no longer works. In this article, we go over possible causes that can prevent you from starting the engine with the Start/Stop button.

In case of an emergency

To get your Mercedes started manually, grab the Start/Stop button and pull it out. Make sure the transmission gear is in Park  (you should see P gear on the dashboard) and you are pressing the brake pedal. Insert the key into the ignition and start the car.

Possible Causes

Smart Key Fob Battery

One of the most common problems that prevent the Start/Stop button to work is a weak battery in the key fob. As the battery in the key start gets old, it will unlock/lock the doors but it will not have enough power to send a signal to the car for the Engine Start function.

If your Mercedes push start does not work change the batteries in your key fob first. Follow this guide to learn how to change the Mercedes key fob battery. 

Note that sometimes new batteries don’t solve the problem. This can be because the “new” batteries may have sat on the shelf of your local store for years and are also discharged as well. Check the production date on the battery packing before you install them.

Press the brake pedal

press brake pedal to start mercedes engineYour Mercedes-Benz will not start when you press the START button if you are not pressing the brake pedal. Only the dashboard lights will turn on. Make sure you are pressing the brake pedal firmly.

Vehicle is locked

mercedes not starting due to key interference high voltageIf you are inside the car and have pressed the lock button on the keyfob, you won’t be able to start the car. Press the unlock button on the keyfob. This will unlock the car and allow you to start the engine with the Start/Stop button.


Mercedes Start/Stop engine function can also stop working when there is interference. This could happen if you are parked near high voltage power lines or near a TV or radio station.

Move to a new location and check to see if your Start/Stop is back to operating properly.

Further diagnostics

If none of the above tips didn’t get your Start/Stop function to work, you can check the fuse for the ignition start circuit. Also, check the brake light switch as it also can prevent the car from starting and is often the culprit if the ignition turns on but the engine doesn’t start.

If the fuse is good and the brake light switch is not the problem, the next step would be to diagnose the car with an MB OBD2 Scanner.

Also note that if you are getting “key not recognized” message on the dashboard, try a different key. The key is not working or is the wrong key.


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