Electronic Engine Managment System

Hi there, I got electronic engine Managment system fitted in my car, and for the past few weeks the symbol start to light up, so I replaced spark plugs and when I removed one of the leads it thorn in half as was still the original leads and was worn out. So I replaced spark plug leads and the symbol stopped flashes. But two days latter I filled the car with petrol and the symbol start to continuously flashes again, please what should I do. Thanks