Benz Tips · KeysYour Mercedes key, explained

Two key systems: DAS 3 and DAS 4

Every Mercedes-Benz key is part of the car's Drive Authorization System (DAS). The key and the car trade an encrypted code every time you start it, and if the code isn't right, the car won't start. Over the years Mercedes has used two generations of this system:

Not sure which one you have? Bring the car or your VIN and we'll tell you in a minute.

Ordering a new Mercedes key: what we need and how long it takes

Elite Benz orders factory Mercedes-Benz keys made for your car's VIN and programs them with licensed MBUSA XENTRY diagnostics, the same factory system the dealer uses. Here's what to bring:

• Your driver's license
• Your current vehicle registration (or the title), with a name that matches the license
• The car itself, or at least the VIN

Mercedes is very strict about key security. That makes ordering a little more involved, but it's a good thing for you: it's much harder for someone to copy your key or steal your car. Don't let the process scare you. We handle the paperwork and make it fast and smooth.

Why Mercedes keys need proof of ownership

Mercedes-Benz classifies keys as Theft-Relevant Parts, or TRP. These are parts that could be used to steal a car or give it a new identity, so Mercedes only releases them to verified owners through registered vehicle security professionals.

• Keys are built for one VIN and only released with proof of ownership: a matching driver's license and current registration, or the title.
• Mercedes will not sell blank or unprogrammed keys, under any circumstances.
• On DAS 4 cars, the car has to be confirmed as present through XENTRY before Mercedes will release the key.

Aftermarket keys: why we say avoid them

Some locksmiths and roadside programs will program a lower-priced aftermarket key to your Mercedes. To do it, they bypass Mercedes security in one control unit. But that security is built into several other control units in the car, and they all check each other. When one doesn't match, it can corrupt the whole chain of command the car uses to decide whether your key is allowed to start it.

Aftermarket keys often work for a while, then:

• Stop working all at once, or
• Cause random no-starts: it starts today, and tomorrow it doesn't.

The slot your key goes into is the EIS, the electronic ignition switch. It's a control unit that reads the code from the key and processes it for the rest of the car. Depending on how an aftermarket key was programmed, the car may not be able to “catch up.” Then you need a factory key plus a new EIS to get it running again, roughly $1,000 more on top of the key.

Factory key or aftermarket? How to tell

1. Look at the tip. A factory key has a black tip. An aftermarket key is usually clear or purple.
2. Look at the center. A factory key has the chrome Mercedes star. On an aftermarket key it's missing, leaving a hollow black star shape.
3. Open the battery cover. A factory key says “Made in Germany” inside. Any other country of origin means it's an aftermarket key. Period.

Key battery: CR2025 or CR2032?

Mercedes keys use a flat lithium coin battery, but not all the same one:

We replace your key battery as part of every yearly service, so you should rarely have to think about it.

Signs your key battery is getting weak

The key gives you warning before it dies, if you know what to watch for:

• Remote windows and sunroof stop working. Opening and closing them from the key stops at about 50% battery, with no message on the dash.
• The red light test. Press any button on the key. If the small red light flashes, the battery is above about 50%. If it doesn't flash, it's time for a new battery.
• A message in the cluster: “Replace key battery” or “Change key batteries.” Replace it soon, or the locks may stop responding.

Key battery dead? How to get in and start the car

A dead key battery doesn't leave you stranded. Every Mercedes key has a mechanical blade built in, and the car can read the key even when its battery is flat.

Getting in

1. Push the release tab on the key and slide out the metal blade.
2. At the driver's door, find the key slot in the handle (some models hide it behind a small cap).
3. Insert the blade and turn it to the left.
4. Pull the handle, sometimes two or three times, until the door opens.
5. The alarm may sound. Put the key in the ignition, or start the car, and it stops.

Starting the car

Your car can power the key inductively, like a wireless phone charger, just long enough to read it:

• Removable start button: pull the Start/Stop button out of the dash and insert the key in its place. Then start the car.
• No removable button: look for the marked key spot in the center console or a cupholder, shown by a small key symbol. Lay the key there, then start the car.

The remote locks still won't work until the battery is replaced, but you can drive the car. Come see us and we'll swap the battery in a few minutes.

Lost a key? We can switch it off

Because Elite Benz has the factory XENTRY diagnostic system with full license rights, we can see which keys are programmed to your car. If you lose one, we check which keys you still have, work out which one is missing, and deactivate that key, temporarily or permanently. Find it later? Bring it in and we'll turn it back on.

That same factory access is what lets us order factory keys at all. Elite Benz is one of the few shops in the Summerville and Charleston area, outside the dealership, that can order and program a factory Mercedes-Benz key. A key from a shop without it is an aftermarket key.

Hidden features in your key

• Close everything from outside. Stand within about a foot of the driver's door handle and press and hold lock. The windows roll up and the sunroof closes, with the car off and you outside it.
• Air it out. Press and hold unlock the same way to roll the windows down and open the sunroof on a hot day.
• Watch the double press. Pressing lock twice in a row turns off KEYLESS-GO. Then when you come back and grab the handle, the door won't unlock on its own. If that's happened to you, that's why. Press lock once when you walk away, or just use KEYLESS-GO.

Car won't start? Call us before the tow truck

If your Mercedes won't start and needs a tow, call us first, especially if it won't go into neutral. Many models have specific tricks to get them into neutral safely, and some tow drivers don't know them. A two-minute call can prevent damage. Read our towing guide before you call a truck.

What does a Mercedes key cost?

If an aftermarket key has already damaged the electronic ignition switch, plan on about $1,000 more for a new EIS. Your exact price depends on the model and key style, and we confirm it with you before we order. Call with your VIN for a quote.

Common questions