Buzzing sound on startup
 

i've got a 95 ex sedan, when i start the car in the morning, it starts normally, but after about 5 seconds i'll hear what sounds like a buzzer go off under the hood, it only lasts a second or two, then goes off... it'll also happen rarely while driving, i have no idea what to check for, theres no CEL on and the car runs fine, im thinking of selling and would like to fix it. any suggestions?