Need help friends! Just got my radiator serviced and on the advice of mechanic, I removed heater pipe to make AC work better. Suddenly, engine check light turned on. The brilliant mechanic (Gawalmandi, RWP) unplugged battery terminal and after plugging it again, the light turned off. But now whenever i lift foot from throtlle, the check engine light turns on and automatically goes off when pedal is pressed and car picks up the speed. What can be the possible problem.