Eis Repair and Testing Service
The Mercedes electronic ignition switch (EIS) is unlike normal car ignition locks that use a metal key blade, the Mercedes Eis switch is like a small socket in the dash which you insert your key into. The key itself it is not a traditional looking key, it is made from plastic and depending on which type you have it is almost triangular in shape with an infra-red panel at the front of it which is inserted into the EIS socket on the dash. The key has a sequential code to ensure the vehicle is not stolen.
When the key is inserted into the electronic igniton switch (EIS) the vehicle will instantaneously carry out a sequence of tests to ensure the correct key has been inserted. Each time the key is inserted, the EIS system will check the key and then ask the ESL (Electronic Steering Lock) system for verification that it accepts the correct key is being used. The ESL system will then look to see if the Engine ECU (Electronic Control Unit) agrees that this is the authorised key being used. Then and only then, when all three control units agree it is the correct authorised key being used, will it allow the “Turn & Start” function to be activated.
Which Mercedes models use the Eis unit
The EIS module/unit is factory fitted to almost all mercedes models and we’re regularly sent units from the entire range from C-Class C220’s to E-class and Mercedes vitos and sprinter are recieved all the time. You can expect the EIS unit/module to be supported on the following Chassis list:
W164 / W168 / W169 / W202 / W203 / W204 / W208 / W209 / W210 / W211 / W212 / W215 / W219 / W220 / W221 / W230 / W639
Which Mercedes models use the Eis unit
The EIS module/unit is factory fitted to almost all mercedes models and we’re regularly sent units from the entire range from C-Class C220’s to E-class and Mercedes vitos and sprinter are recieved all the time. You can expect the EIS unit/module to be supported on the following Chassis list:
W164 / W168 / W169 / W202 / W203 / W204 / W208 / W209 / W210 / W211 / W212 / W215 / W219 / W220 / W221 / W230 / W639
Mercedes EIS / EZS Module Problems
Here we list some of the more common faults of the Mercedes EIS/EZS unit:
Key wont to turn when inserted into eis
Car wont start
Steering lock will not release
Intermittent key faults and difficulty to start
Mercedes EIS / EZS Immobiliser Key Module Problems
Here we list some of the more common faults of the Mercedes EIS/EZS unit:
Key wont to turn when inserted into eis
Car wont start
Steering lock will not release
Intermittent key faults and difficulty to start
Many EIS’s can be easily fixed, with replacement parts or a service exchange unit, if after testing a unit cannot be repaired or replaced with a reconditioned unit we can supply a new unit which is fully plug and play requiring no other programming in most cases.