hello everyone.
 

My 2001 S430 mercedes Benz with 85.000miles runs and feel like a new car but lately with the weather getting colder the ignition switch don't turn at all...a person told me to use a blowdryer which most of the time works but now since the weather is even colder it is not going to work anymorenow I found out that it might be the relay in the alarm system so if anybody knows anything about that problem please let me know.if I get the car started I can drive it find hours no problems but if the car sits for a long time the problem start again the ignition switch locked again when the car is cold....

Same problem using both keys?

Check your batteries in the remote?

Martin

No batteries needed to crank the engine. The key is powered inductively by the ignition switch. :)

Sounds like your EIS module is starting to fail, or you have bad keys. I would not be using a hair dryer on that, theres nothing mechanical its all infrared.

My car did that. Pretty common in the C series anyway (post 97). $1500 at the dealer. Negotiate a loaner. Good luck.