Problems with the key of your Mercedes-Benz? Let’s look at the possible causes and solutions.

I insert the key, and the car does not start.

On any given day, you pick up your car insert the key into the starter, but nothing happens. The key to your Mercedes Benz won’t turn or start the car. Not even that characteristic noise that occurs when the car’s steering wheel is unlocked is heard. Horror! The car won’t start and is completely dead.

The problem in starting a Mercedes Benz can be caused by various reasons, from a completely discharged battery, through a problem with the car key, to a much more serious electrical problem. If you need to repair your car key, make a duplicate key, or if you have any of these problems, read on.

How does a Mercedes Benz key work?

When inserting the key of our Mercedes Benz in the ignition, several simultaneous operations begin to be carried out. Thanks to the work of our vehicle’s electronic ignition control module (EIS). When we put the key in the ignition, our key receives energy thanks to the coil that is in the EIS through a phenomenon called induction. And it is also there when the data stored in our key is exchanged with the car using the infrared transmitter inside the key of our Mercedes Benz in order to validate our key and driving authorization. At the same time, and as part of the same process, the steering wheel of our car is unlocked, and the vehicle’s engine is started. This happens quickly and starts when we put the key in the ignition.

A problem with the car key or the immobilizer module Mercedes EIS – EZS

• You are unable to turn the key
• You can turn the key, but the car won’t start.
• Steering wheel won’t unlock
• Intermittent key and ignition failure
• Key sometimes turns and sometimes doesn’t.
• Does not start when the weather is very cold.

The Mercedes Benz electronic immobilizer system, baptized as the Driving Authorization System (FBS), is the one that reads the car’s electronic key. Checks the correct programming of the key and the entire system’s operation each time the key is inserted into the ignition. Then try to start your car. In most modern systems, it is not even necessary to enter the key. A malfunction in the immobilizer system or a problem with the car key will prevent this system from working properly. And as we always remember, for all this and more, you must have a copy of your Mercedes Benz key.

Mercedes Benz smart key remote control

The key itself may be the reason the car won’t start. Keep in mind that, on many occasions, the key can open the doors but does not start the car since the command is independent of the transponder in the car key, which is responsible for identifying and validating our key for starting. In some cases, the transponder coil may be damaged or disordered, or even some other component on our remote control board may be damaged. Fortunately, on some occasions, a Mercedes Benz remote control can be repaired, or if this is not possible, we can program a new key in our car. As you will see below, making copies of Mercedes Benz keys is not only possible, but it is also quick and cheap.

The steering wheel won’t unlock

When you insert the Mercedes key into the ignition, the electronic steering wheel lock should disengage and allow you to move the steering wheel freely. On some models, if the key won’t turn in the ignition, you can try turning the steering wheel while trying to turn the key. The steering wheel will feel completely locked, although you can try to move it in one direction and another. Try moving the steering wheel slightly back and forth while at the same time trying to turn the key in the ignition. DO NOT ATTEMPT TO FORCE THE KEY INTO THE STARTER CYLINDER. Many vehicle manufacturers include the steering wheel lock as their safety equipment.

Problems with the key and the starter cylinder

The ignition cylinder may have a problem if you have a key that uses the traditional metal blade instead of the remote control. Although most Mercedes-Benz cars use what is known as SmartKey, some models, such as the Mercedes Benz ML, used a blade key even up to 2005. As we discussed a little above, make sure that the steering wheel is not in a locked position, then place the key in the cylinder and try to turn it gently, trying to start the car. Remember not to use too much force or try to pick the lock.

Being a purely mechanical system, keep in mind that over time it will become more and more difficult to turn the key when starting, as the internal parts suffer natural wear. Fortunately, car locks can be replaced or repaired like any other lock. It is in this type of situation that we understand the importance of having a copy of your Mercedes Benz key.

Faulty Electronic Immobilizer System – EIS-EZS Problems

Another of the possible causes why the key of our Mercedes Benz does not turn at startup can be caused by a faulty EIS. In fact, there has been a phenomenon in some of these modules, to say the least strange, in which the vehicle starts perfectly on a hot day but has problems starting on a cold day. Although it may sound strange at first, it is a widely reported and known problem that has a technical solution. In some EIS – EZS modules, the microprocessors used are faulty and problematic at low temperatures. This is usually resolved by replacing the faulty component in the EIS electronic module. This is just one example of the many problems these components can present.

Problem with the ECU – Engine ECU

The Electronic Engine Control Unit, usually known as ECU, is another possible reason why your car may not start. If this is the case, it is best to turn to a trained professional and the necessary equipment to diagnose the problem in your vehicle. The repair of the car’s control unit is often a possibility. In other cases, it will be necessary to install a new unit to replace the failed ECU to solve the problem. Remember that you can either just swap the drive for another of the same model, as this will not work. These types of modules require prior programming and subsequent programming in the car to function correctly.

Car battery problem

If the car’s battery is defective and does not provide the necessary voltage for the electronic ignition switch EIS and ECU to work properly, the car will not start. If the battery does not have the minimum necessary voltage or is discharged, the CAN communication may not work properly. As we mentioned above, the EIS in Mercedes Benz has a coil that is used to induce a magnetic field in the Mercedes smart key. This is essential to power the key and exchange information between it and the EIS module, which will be in charge of checking our key and allow the start if the key is correctly programmed.

Here are a few final tips…!

• Clean your key’s infrared emitter/receiver area with a dry cloth.
• Do not try to clean the EIS – EZS with any type of liquid.
• Check the car’s fuses
• Always prevent the car from running out of battery while the key is in the ignition.

If you’re facing any of the above issues in your Mercedes and looking for Locksmith services in Tampa, rely on us. Our Automotive Locksmith in Tampa Bay can handle every make and model of car without any hassle. Count on us whether you need a car key replacement or want to repair your ignition.