DaveM1603

Don’t know if this helps, an extract from the Oct I owners manual. Synchronisation If the vehicle cannot be unlocked by actuating the remote control system then it is possible that the code in the key and the control unit in the vehicle are no longer synchronised. This can occur when the buttons on the radio-operated key are actuated a number of times outside of the operative range of the equipment or the battery on the remote control was replaced. This means it is necessary to synchronise the code as follows: › press any button on the remote control key; › pressing of the button means that the door will unlock with the key within 1 minute.

I assume the hissing is normal as my Octavia lll Estate 2.0 TDI SE L 2018 has the same hissing when you listen at the back