Mazda Repair: 2000 Mazda 626 check engine light, 2000 mazda 626, car mechanic

Question

The check engine light in my car goes on/off by itself..
Tried to diagnose from car mechanic,he said no problems, so
he reset it,  but came back after 2-3 days. Car works fine,
but check engine light is on for abt more than a month and
annoying.  

How Do I reset the check engine light for 2000 Mazda 626
myself? Is there a way to know what excat problem could be
. how to i get a permanent solution.

Thanks in advance

Answer
if you had it diagnosed and there wasn't any codes then you probly have a faulty engine light, you can try removing the battery cable and press the brake pedal for about 10-20 secounds then reconnect the battery, that's how i've reset all the mazdas i've worked on