Nilantha, thanks for the advice.
my mechanic is one of x-a*w guys name "Ravi" at Kelaniya and he normally does the same thing and he always do the mannual ECU reset and working fine for me (and most of my friends). once, just after his mannual reset, i took the car in to agents and did the scan, and found that everything is set to it's default values with out any issues.
My thought is to take our cars to well expericed mechanics rather putting here and there. what do you guys think?