Mercedes W211, W219, W209 Keyless GO not working? A diagnostic guide
This guide covers Mercedes E-Class W211, CLS W219 and CLK W209 with Keyless — opening, locking and starting the car without taking the key out of your pocket.
Keyless can be temperamental in these cars. In our experience, the door handles are usually the part that fails. The checks below will help you find out whether repairing a handle is enough or whether there is a wider problem.
Keep the key in your pocket. Do not insert it into the ignition or press any buttons on the remote.
1. Does any door handle work?
Test every handle: opening and locking separately.
Yes, at least one responds. That means the Keyless system as a whole works and recognizes the key. The handles that do not respond are faulty, and you can repair them.
None of them works. Check the trunk.
2. Does Keyless work at the trunk?
Test opening with the car locked, then locking the car with the Keyless button. Test both buttons.
Yes, at least one responds. The Keyless system as a whole is working; only the door handles are faulty. This is common in these cars: the handles usually fail much sooner than the trunk control.
Neither opening nor locking works. Check the button on the gear selector.
3. Does the selector button switch on the ignition?
Yes, only the ignition works. All the exterior buttons — door handles and trunk — may have failed. There could also be a problem with the exterior antenna. Further computer diagnostics are needed to be sure.
Nothing works. Replace the batteries in the key, then start the checks again.
Still nothing? Have the car checked with a diagnostic computer at a workshop that services Mercedes vehicles.
4. Check the messages on the instrument cluster
If none of the Keyless controls works, check the messages on the instrument cluster. Switch on the ignition, pull each handle in turn and press its locking button while watching the display. Check every door — you may see a response at only one of them.
A ‘Key not detected’ message means the car responds to the button but does not recognize the key. In that case, computer diagnostics are necessary.
Only the door handles are faulty? That is good news.
You can repair them easily with our repair kit:
The kit contains everything you need to refurbish a handle. We show the entire repair step by step in the instructions.
It is a cost-effective solution: you repair only the part responsible for the Keyless function. The original handle housing stays in place, so you need neither a complete new handle nor repainting. Your car keeps its colour and original appearance.
See repair kits in the MBKeyless shop →
A closer check of the original handle
If you want to be sure before ordering a kit, you can check the buttons and inspect the rubber seal.
Inspect the rubber seal
Look closely at the thin rubber membrane around the opening button. It protects the electronics in the original handle from water. Over time it wears and cracks. Look for tears, cracks and places where the inside of the handle is exposed, as in the photo below.
This is what a damaged seal looks like. Water reaches the electronics through this hole.
Listen for the click
Check opening and locking separately. Both buttons should move smoothly and click distinctly. Listen for the click in the handle itself, not the sound of the door lock. If you have a working handle, compare it with the suspect one.
Watch for a missing click, sticking or a button that remains pressed. Rough movement, rubbing or grinding under your fingers is also a warning sign. This can happen when water gets in and corrosion develops. A click alone does not prove that the switch is passing a signal.
This is what the inside of an original handle can look like after water gets in. Corrosion is visible on the electronics.
To inspect the seal from inside and check your handle, remove it from the door. We made a video showing how:
Watch the door handle removal video on YouTube
If you find these symptoms, you can be sure the handle is faulty. In that case, we recommend repairing it with an MBKeyless kit. We show the repair step by step in our instructions.