Have the dealer install a new ignition switch, and they will program it to match the VIN of your Mercedes-Benz. This is an expensive repair that can cost several hundred dollars. If they conclude that the Ignition Switch (EIS-EZS) is the culprit, you will be told that the switch must be replaced. You may consider taking your car to the dealer or an independent shop and having them troubleshoot the problem. Hopefully, there are fault codes that will point you to the problem.ĭiagnosing Mercedes ignition problems isn’t a simple DIY job. If the ignition turns intermittently, consider yourself lucky and scan for codes. The only issue here is that if you can’t turn on the ignition, you can’t power on the OBD2 port and the scanner. If you don’t have this scanner or know of a shop that does, a possible alternative would be to use a YOUCANIC scanner. This scanner should still retrieve fault codes when the ignition is off.

Try scanning your Mercedes-Benz for fault codes. If the other key works, keep using it for a couple of weeks to verify that the issue is the key and not the EIS. If you have a spare key, try to see if you are experiencing the same symptoms with the other key. How to fix Mercedes Ignition Switch ProblemsĪ defective key can very well cause these symptoms. That’s not necessarily the only solution see alternatives below. They will recommend that the module be replaced. Mercedes dealers don’t repairer a bad EIS-EZS module. While it can be diagnosed with Start Diagnostic Scanner used at dealerships, it can’t be repaired with this scanner.

Connecting jump-starting cables while the key is in the ignition.ĭuring any of the above scenarios, the EIS-EZS may lose its memory.

For example, some common reasons why the ignition module failed are: Mercedes-Benz ignition switch (often called immobilizer module) can become faulty and, in some cases, due to user error.

I can turn the key, but the car won’t start.

Unable To Turn The Key, Unable To Start The Car.

The key may turn, but the instrument cluster lights don’t turn on.

The key doesn’t turn during cold weather.

The key does not turn in the ignition due to failed EIS.

Possible symptoms of a failed Mercedes-Benz include: This problem can affect various Mercedes-Benz models, including E-Class, S-Class, C-Class, CLK-Class, ML-Class, SL-Class, etc. This issue is often caused by a defective key, a bad shifter module, a failed Electronic Ignition Switch (EIS), the EIS-EZS, or a bad steering lock module (ESL). A problem that Mercedes-Benz owners may face is the key no longer turns in the ignition.

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