Mercedes-Benz-C63_AMG_Coupe_Edition_1-20

Mercedes Benz EIS/EZS Ignition Switch

Repair - Replacement Service

Mercedes Benz owners may face a problem with the key no longer turning the ignition or not starting the car. This is often caused by a damaged/defective key, a failing/failed Electronic Ignition Switch (EIS/EZS), or a bad Electronic Steering Lock (ESL). When a key is inserted into the EIS the immobiliser system will instantaneously carry out a check to see if its a correct "programmed" key that has been inserted. The EIS will verify with the ELS and Engine ECU to check that it is a correct key and if the units agree it will authorise the vehicle to be started. 

Common Mercedes EIS/EZS Ignition Switch Problems:

  • Key won't turn when inserted into the ignition.

  • Key won't turn in the ignition during cold weather. 

  • Key turns in the ignition but the car won't start. 

  • Intermittent key faults and non start. 

  • Key turns the ignition but dashboard doesn't turn on. 

  • Unable to unlock the Steering Lock

Reasons for the EIS/EZS Failure

  • Low Battery Voltage

  • Power Surge

  • Connecting jump-starting cables while the key is in the ignition. 

  • Corrosion/faulty processor. 

Mercedes Dealership would advise you to purchase a new unit as the EIS Module cannot be repaired or reflashed using the Mercedes Star Diagnostic System. That's not necessarily the only available solution. ​

Solutions to the Ignition Switch Problems

First of all, if you have another key for that vehicle check if you experience the same symptoms with the spare key as it could have been caused by a defective key and not a failing EIS/EZS-ESL modules. 

Another option would be to get the EIS/EZS tested and either repaired or replaced with a unit from a donor car. A donor unit would need to be programmed to the vehicle so that the stored VIN is matched in all modules. 

We are able to offer a testing and repair service as well as programming a replacement donor units. 

Mercedes Benz electronic ignition switch Repair service for models such as:

  • W202 W203 W208 W209 W210 W211 W220 W215 W219 W230 W463 W639 W906

  • Mercedes-Benz A B C E G S SL ML GL SLK Class

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