When did they get that and how? Closing all the doors, locking with the remote, then unlocking again should be all that is needed. If the EKA is needed it will normally say (if in English), Engine Disabled, Press Remote or Enter Code but entering it isn't going to do any harm as long as your door latch microswitches are working, you have the correct EKA and you enter it correctly.
So have him close all the doors, put the key in the lock, turn it to lock and press the lock button until the LED flashes, then turn it to unlock and press the unlock button until the LED flashes. That should re-sync the key.
When you do the 4 turns to lock, the hazard lights should give a single flash on each turn. Then when you start entering the code, which must be done slowly and positively, for each turn the green sidelight lamp on the dash (the one between the indicator lights) should flash with each turn. First number turn to unlock, second to lock, third to unlock, fourth to lock, then turn to unlock and all doors should unlock. Get it wrong 3 times and it will go into Keycode Lockout and won't do anything or accept any key turns until that goes out (after 30 minutes). If latch microswitch is worn, it will probably be the keyswitch so it won't see the turns of the key in one direction or the other.
I had to check but you don't always get the chirp, it depends on whether it has been programmed to chirp or not in the BeCM settings and if you alarm sounder is still working and connected. An awful lot of alarm sounders have been disconnected as if the car was fitted with the battery backed sounder, the internal NiCd batteries will have died years ago so people just unplug it.
Tell him to enter the numbers slower than on the video, his car obviously has perfect microswitches so will accept it, if they are starting to get a bit worn, pausing for a second on and between each turn is a better way.
I wouldn't get too hung up on chirps and lights flashing or not. The real test is whether or not your EKA works, assuming you have the right code. If the EKA does not work you are pretty much hooped. Not sure if installing a new door latch will get you going as no one recommended that to me when my 98 was disabled.
Security system is worst feature of these cars.
Or best depending on whether you are an owner or a car thief. I've successfully entered the EKA on a car with a dead latch by plugging a working one in (but not fitting it) and operating the levers to simulate key turns. You can do the same by grounding the correct wires in the correct sequence.
'Falscher code' means 'wrong code', which indicates the system has been tampered with (3 failed EKA attempts) or at least thinks this is the case. You'll need to wait 30min with ignition in position 1 for that message to clear, before it will accept the EKA.
Also don't get hung up on lights etc while doing the EKA, I've found those can differ from car to car. Just make sure he takes his time putting in the code, and waits for the central locking to operate all doors when he unlocks (after putting in the 4 digits). Sometimes it doesn't react right away, even if it's just a delay of a second, it will seem like an eternity but a great relief when the doors do unlock.
Thanks for confirming that, I've been exchanging PMs with the OP as I've given him hints that don't really belong on a public forum and have worked out that Wrong Code in German is the same as Keycode Lockout in English. The giveaway is that it is still displayed if you turn the ignition off and take the key out.
Perhaps they insisted with the door lock and that make it think it was a wrong EKA? It is strange that I have that message, because the mechanic had no idea of the EKA procedure, not even the existence of it, so the probability of an "incorrect" code being entered is very low, even more so if ones considers that you need to cycle 4 x to LOCK prior to the system even accepting/reading an incorrect code.
When do the 30 min start to count? And it is dependent on having a battery connected?
The car was left without a key overnight, but with a dead battery...