Dunno what the heck was going on today when I went to Pinnaroo carpark (parked just to the right of the swings facing the beach under a big tree)... and my remote central locking didnt work. Thinking it was just dead batts I didnt care much, but then a couple of other guys parked next to me and had the same problem...
I've heard of people using jammers to prevent people locking their cars using the remote (Some people don't realize that the car didn't lock), and then they just help themselves to the car after the owner has gone.
433 MHz and 304 MHz are fairly standard frequencies for aftermarket remote immobiliser/alarm, central locking systems to operate on. These frequencies are common for lots of other applications. If someone transmits on these frequencies as you are trying to activate your security system then it will "block" the code being transmited within the frequency and obviously your car security will not activate. Always ensure once you have activated your security system your indicators have flashed, or for the cheaper system with no flashing indicators ensure you have heard the audible clunk of the central locking actuators operating.
There is a way to beat this by fitting a code hopping remote security systems that operate somewhere between 800MHz to 915MHz but these current systems are cost prohibitive for the average motor vehicle and more aimed at the prestige car market.
