hazabenz

Went to start my '99 E300 today and nothing. At first the key went into the Ignition and turned but the car didn't crank or start at all.
Pulled key out again and now the steering wheel is locked and ignition switch is locked too. It will not register the key whatsoever. Key fob also stopped locking and unlocking car. I do not have any spare keys, so I'm stuck with what to do next.
-Replaced key batteries, key fob works, check IR light on the end of the fob
-Cleaned the lens on the key and ignition switch
-Checked Fuses, all good
-Battery voltage checked in the car

Are there any other things I should check? Its almost like the car lost the recognition of the key completely.

davmil2002

I think they can make you a key with the VIN. I had a locksmith make me a spare and it works fine. He knew how to connect with the Mercedes computer and it programmed the FOB. Cost about $200 as I recall.

raymond g-

read MBUSAs policy here which, for the most part, will require the car be brought in to the dealer now. Smartkey now averages $300
https://www.benzworld.org/threads/ca.../post-18332241

OP didn't identify car battery voltage but if it isn't in the high 12 under load the ignition module may not function

i keep this inexpensive doohicky in my toolbox. I SEE THAT EBAY reference is dead. Seems the keywords on ebay are "Car Key ECU Test Coil Induction "

Here is

Amazon link

Amazon link

to similar

You Tube

MacVidMB-V8

Keys like this can frequently be fixed.

Plutoe

forget all the HS have you checked your K40 relay which on diesels are typically under hood passenger side