Why does it beep 12x when I start? - 1999 Mitsubishi Montero Sport

Are there any warning lights present when it beeps? Seat belt warning light, door ajar light, traction control? anything?

Dead Battery

Ok, first off do you have a chiped key? look on the side for a resistor symbl if yes try a spare key if you have one. secondly is the theft light flashing? third option turn the key to the on position wait 15 and try to start the car, if it is your security system this will sometimes deactivate it

parking sensor beep?
if yes then if one of the sensor fails then all system goes off and keeps buzzing

The alarm started beeping when I was backing up. And then it was also beeping when I had stopped and now it is beeping when I am in drive. This just started happening. I got the car washed at a car washing place, could this have something to do with it?

Try hooking your seat belt, put it on, before you try to start the car.

does the airbag light come on when you start vehicle? If the lamp is out it will give an audible beep.

mine used to beep alot when the blinker was left on my mistake, go down road and merge into left lane leaving the blinker on ,beep,beep beep beep, alot till i turned off blinker ,hope this helps thanks robert b.