Only slightly similar but, my daughter has 1999 C280. One day, key would not turn in ignition. She only had one key so car was towed to the dealer and an additional key was ordered. The dealer started with a limited diagnosis but stopped when the new key came in and the car started. After reading up on the key not turning I was preparing her for a EIS replacement which is $1000+. Dealer advised not to use old key because it may corrupt system. I took apart the old key and examined joints with a loupe and cleaned the coil and bulbs of dust. We are waiting for an opportune time to try out the old key. She also bought a second new key. Both new keys have a problem in that sometimes after a start the car would shut down. Subsequent starts are fine and the car runs fine until a random start would fail. Dealer says next step is WIS.