The key fob for your 2005 Mercedes E320 is more intricate than just a simple remote. It’s important to understand that the battery inside your Mercedes W220 key fob primarily powers the remote functions like locking, unlocking, and the alarm system. Contrary to some beliefs, a dead key fob battery will not prevent you from starting or driving your car.
The Electronic Ignition System (EIS) in your E320 utilizes induction coils around the key slot. When you insert the fob, these coils generate a current within the fob itself. This induced current activates the fob’s internal circuits and the infrared (IR) emitter at the tip. The IR signal then communicates with the EIS to enable starting and ignition, even if the fob’s battery is completely dead. Therefore, if your 2005 Mercedes E320 is experiencing engine shutdown issues, it is highly unlikely to be related to the key fob battery. A more probable cause would be fuses or relays within the vehicle’s electrical system.
However, a functional key fob battery is necessary for remote operations. If your key fob battery is dead, you will lose the convenience of remotely locking and unlocking your doors, trunk, and activating or deactivating your car’s alarm system. In such cases, you would need to use the physical metal key to manually unlock your Mercedes. Be aware that manually unlocking with the metal key might trigger the alarm until you use the interior lock button to disarm it.
Furthermore, the key fob battery powers the comfort convenience features. By aiming the IR emitter at the black sensor on the exterior door handle and pressing and holding the unlock button, you can remotely roll down all windows, open the sunroof, and even activate the ventilated seats if your E320 is equipped with this option. Holding the lock button reverses these functions, closing windows and the sunroof. Replacing the battery in your 2005 Mercedes E320 key fob is a straightforward process to restore these remote functionalities and ensure seamless access to your vehicle’s convenience features.
