Key Knowledge A brief history of Mercedes-Benz electronic keys

Richard Simonds

This brief look at electronic keys provides an overview of the development of modern Mercedes-Benz ignition keys, and highlights some of the design features of variations over the past thirty years.

Key Knowledge

A brief history of Mercedes-Benz electronic keys

Article and images Richard Simonds

This brief look at electronic keys provides an overview of the development of modern Mercedes-Benz ignition keys, and highlights some of the design features of variations over the past thirty years. The names have also evolved and in some cases two names (Smart Key and Keyless Go) have been used interchangeably. Generally, a feature set is carried forward with new functionality added to the subsequent type of key. It is typical for Mercedes-Benz to introduce a key to one model and then roll it out to other models within a year or two. Thus, the year when a type of key was introduced may not be relevant to your specific year and model. When you want to compare this information to your model of Mercedes-Benz the very best resource is your Mercedes-Benz Operator’s Manual.

Note: Replacements for some older electronic keys may not currently be available, so treat your older keys gently and carefully.

Types of electronic keys

In 1990 Mercedes-Benz introduced the “flip key / switchblade key” (1) that allowed for remote door locking with the fob using an infrared transmitter/receiver. However, the fob had a flip out double-sided key with “teeth” on both top and bottom – notches that controlled which lock would work with the key, allowing the key to be inserted into the ignition, door, trunk, or tailgate with either side up.

Mercedes-Benz filed a patent in 1997 (based upon a Siemens design from 1995) for a Smart Key to replace the infrared key. This was introduced in the 1998 S-Class. The new key had a plastic fob with controls for the locks and the ignition. With this key the fob was placed into an ignition slot and a rolling code verified it was the correct key for the vehicle. Once verified, the system allowed the engine to be started. The optional keyless feature allowed the Smart Key to remain in the driver’s pocket or purse to start the engine while buttons on the fob controlled the door and trunk/hatch locks.

This key also had a removable metal key that could be used to unlock/lock doors, trunk/hatch, glove box, and trunk/hatch floor lock. When those locks were set manually, they could not be accessed using the remote key fob. Finally, a red panic button would cause the horn to honk and the lights to flash in an emergency situation.

In 2003 Mercedes-Benz introduced a fully functional “proximity” smart card to provide access and engine start/stop. The new system was called Keyless Go. However, it proved not to be durable and in 2004 the same functionality was put into a newly designed key fob (2). This proximity function allowed the user to unlock/lock doors (including the fuel filler door) and to start/stop the engine with a push button on the dash. Some versions of the key could be associated with specific settings such as seat and side-view mirror positions. The idea of “his and hers” keys with settings for each driver proved troublesome when keys were used randomly by each person. This function was discontinued after a year of complaints.

In 2012 Mercedes-Benz created the now-familiar version of the Smart Key that made Keyless Go a standard feature (3). The Engine Start/Stop button could be removed and the key fob inserted into the ignition key slot to manually override a malfunctioning remote starting operation. This new system provided higher security by using a dual-mode signal system. The new keys used both infrared and radio signals to communicate between the key and the vehicle and its various control modules. This fob also contained a small removable mechanical key to access the trunk/hatch, glove box, and trunk/hatch floor lock.

For the 2020 model year, Mercedes-Benz modified the key fob (4) and Engine Start/Stop functions so that the dashboard button cannot be removed to start or stop the engine in the event of a dead key battery or a malfunctioning key. Instead, there is a key symbol on the floor of one console cup holder. Placing the key into that cup holder allows the car to verify the key using a passive RFID coupling. This change was also made to overcome an occasional problem with the previous generation in which the Smart Key could not be removed from the ignition slot due to a communication malfunction.

Electronic trade off

As all vehicles become controlled by electronics (growing from about 1 percent in 1960 to almost 30 percent in 2020) the Smart Key system has also gained functionality. Electronic control provides higher efficiency in many systems, adding precise control of engine emissions, the transmission, and numerous other vehicle systems. Electronics make operating your vehicle much easier and safer (think of Parking Assist, Lane Keeping Assist, Braking Assist, and the list goes on).

However, electronic systems do not always have the extended life span of mechanical systems, and when they fail they can be much more challenging to replace. In reality, electronics are present in virtually every aspect of our lives, and the benefits of technology always come with limitations. Unless you choose to live in a remote area of our planet without access to the power grid, that tradeoff is just part of modern life.

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