I think if the sensors are at fault then it would beep 3 times only. Then if you are having a continuous beep or longer then 3 it's the fuse. Best way to check it to put it in reverse and see if your lights come on if they don't then it's the fuse.
@@josephborg5938 eBay I believe! Just typed in ix35 reverse sensors. Some aren't the same. I had the wrong ones sent to me the first time. I think they cost £30