I have '02 C320. Sometimes, especially during cold weather, the SmartKey will not start the car. The Radio/CD/lights will work. But I'm unable to turn the key in the ignition. After a few minutes of pulling in and out, It'll allow me to turn it and turn the car on.

Sometimes it won't even unlock the car. I'll have to press the unlock button for a few minutes (2-5 mins) and then it'll unlock.

I'm going to replace the batteries in one of the keys and see if that helps.

Thanks in advance.

 

have you checked your mercedes alternator? spark plugs? ignition module? or it might be because of some dirty connection, try to clean everything. give us an update regarding the things that you noticed. good luck