Have Mercedes Questions? Ask a Mechanic for Answers ASAP
Hi, my name is***** apologize for the long wait on this question. If you have 1 key that will not start the car you simply have a bad key. You can take the car to the Mercedes dealer and have them try to reprogram the key to the ignition switch using the Mercedes Star Diagnosis tester. If the key cannot be reprogrammed you will need to purchase a new smart key from the dealer.
Let me know if you need further assistance.