The EIS switch module is fitted to most modern Mercedes-Benz vehicles and is the name given to the Mercedes electronic ignition switch. When repairing our first EIS immobiliser key module fault, never did we think this would become such a wide spread problem. We are seeing units sent in from all over the world every single day and the fault is affecting all models fitted with an EZS / EIS switch system.

We have found similar faults within the Electronic Steering Lock (ESL) and we request all customers to send in their Mercedes ESL unit along with a key and the EIS together so that we can connect them on the bench and test all parts thoroughly. The most common fault with an ESL is the lock not engaging or disengaging but whatever the fault, we are able to replicate it on our purpose built test rig and repair accordingly.

If your EIS switch unit has failed completely, it can throw out the key and cause the key to become faulty as well. It doesn’t always happen but we have seen it quite a few times. If you insert both keys into a faulty EIS module, you can expect both keys to potentially fail. Not only can we repair key faults, we can also build you a new key if required.

Our EIS, ESL + Ignition Key repairs have become extremely popular amongst Mercedes owners and we maintain an impeccable success rate. Our purpose built testing rig can test the units in all conditions, which does include simulating extreme weather conditions where customers find their units failing in cold temperatures.

Check out our extensive Mercedes EIS / EZS Repair article and if yours is faulty, get in touch to find out how we can help you!