2006 Toyota Corolla Engine light on comes on

After starting the car the engine light remains on, i have gone through the regular service like oil change oil filter change etc. one of the electrician removed the battery terminals for 10 seconds, & replugged it, the light vanished, but after every 2 or 3 days it again comes back & i have to do the same,

any idea what could be the issue, the battery is perfect,

Thanks