1) The normal reason is that the car, for some reason, cannot auto-lock when one has walk-away auto-lock enabled. The simplest thing to fix this is to walk up to the car and press the door handle lock (or Fob lock icon). If this is the cause, it will lock the doors, and not continue beeping. 2) If you walk away from the car without turning it off first. May sound obvious but its easy to do with a car that doesn't typically run any engine you can hear. 3) If the headlights are set to ON instead of AUTO and you turn off the car you may hear one or more beeps. i.e. You should either turn off the lights or select auto. 4) car will beep if a door or trunk open when driving. The car also does a verbal warning if the passenger tries to undo their seatbelt while the car is still moving. 5) The car may not let you lock it if another FOB is still in the car. This happens to us sometimes if my wife leaves her purse in the car, with FOB in the purse. 6) Separate but seems related, the trunk won't let you close it if your key is in the trunk. Maybe seems self evident, but the car is 'smart' enough not to let you do this to yourself. 7) the car beeps twice when recalling a driver seat position if it's different than the last driver. 8) The car beeps when one has a charging schedule but decides to charge immediately. 9) Road departure mitigation (if driver doesn't respond to leaving road). Anyway, it might be nice to document beeping in this thread. Sorry if too redundant with other threads but couldn't find any compilation of beeping. Also, since the car does single beep (for many things) those may not be worthy of mention. Typically one gets frustrated only on the occasions the car does 2 or more beeps and you can't immediately figure out why.