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MB Paul
MB Paul, Mercedes Technician
Category: Mercedes
Satisfied Customers: 4317
Experience:  Mercedes Benz Qualified Diagnostic Technician
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C200 fob wont switch on ignition

Resolved Question:

C200 fob won't switch on ignition
Submitted: 3 years ago.
Category: Mercedes
Expert:  MB Paul replied 3 years ago.

MB Paul :

Hi,

There are several points of failure on the car for this problem - the key sends a signal to the EIS (electronic ignition switch), if the EIS detects the correct key then it sends a signal to the ESL (electronic steering lock) to unlock the steering, once unlocked it sends a signal back to the EIS to allow the key to turn & the engine to start.

So in theory it could be the key, the EIS or the ESL.

Key failure is a common problem & it is wise to get a replacement key to rule out any key problems - batteries are only needed for the remote central locking & not needed once the key is inserted in the ignition to turn the key, so batteries would not be an issue.



The main vehicle battery should also be checked to ensure it is in good order.

If the car still has this problem with a new key then diagnosis on Mercedes STAR diagnostic tool is required to see what signals are being sent & if any codes are stored.

The key is the most common failure, followed by the EIS & the ESL being the least problematic of them all.

Both the EIS & ESL need coding on STAR after installation before they will work.

Best regards, Paul

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