To program a Mercedes key, point the key at the car before pressing the lock/unlock button twice. Then, within 30 seconds, turn the ignition switch to position II. These instructions apply to A class Mercedes with flip type rectangular keys.
To program keys for C class, E class and SLK, begin by pointing the remote control at the receiver. Then press the lock/unlock button, and manually lock the vehicle within 30 seconds using the boot lock.
Alternatively, point the remote control at the receiver, and press the lock/unlock button. Then switch the ignition on within 30 seconds. Alternatively, you can turn the ignition switch to position II.
For M class Mercedes, begin by turning the key to position II in the ignition lock before turning it to position zero in the lock. Remove the key, and press and hold the lock button within 60 seconds. Press the unlock button five times while holding the lock button. Then check all functions, and if it does not work properly, repeat the process.
If you have trouble programming your Mercedes car or you have a bladeless key, seek professional help. Bladeless keys cannot be used on different vehicles other than the ones they were supplied with.