I tried today to make a keyless key on a Mercedes benz s350 2009 with xhorse vvdi mb and FBS3 key. but the keyless function does not work, error: The key is not recognized.
At the same time, only keyless does not work (The central lock is working by inserting the key into the ignition lock, the car starts, the doors close/open if you press the buttons). Keyless go did not!!!
Change FBS3 key frequency does not work. It is not a problem of frequency.
Neither Xhorse nor CG keys will work for older non-BGA cars before 2009.
You need original for those.
The keyless function will not work if the original key has two batteries, you need to use the original factory key to prepare new key.
If you generate OEM key, not Xhorse key but had problem with OEM key keyless function, check following tips:
1). If the original remote with only one battery, the OEM key you use should be only one battery as well.
2) You use an used key, can’t guarantee if was damaged during the renewal process.
3). You must select V41 file to make original remote.
How to Change VVDI MB FBS3 KeylessGo Key Frequency 315MHz 433MHz?
Can VVDI MB Renew V08 Keyless Mercedes keys?