There are more than 40 documented reasons why the Check Engine light on a car's dashboard could come on. They range from major to minor issues, though can affect engine life efficiency and performance. The Environmental Protection Agency estimates that more than 6 million Americans (and therefore, a half-million Canadians) are currently driving cars with Check Engine warning lights on.
Automobiles that are model year 1995 or newer are subject to stricter federally mandated emissions standards known as OBD2 and have a catalytic converter to reduce pollution. The on-board computers trigger the Check Engine light whenever exhaust emissions fall outside the normal range and may damage or indicate damage to the catalytic converter.
The lion's share of issues end up being due to a lean or rich air/fuel mixture, a bad spark plug or plug wire, or a failed oxygen sensor, and anything that causes poor engine performance or inefficiency could trip the light. Because a car's on-board computer systems are interconnected, seemingly unrelated problems with the transmission, anti-lock braking system or even a loose gas cap could also trigger a Check Engine warning.
Have a qualified service technician can perform a thorough diagnosis as soon as a car's Check Engine light comes on. The warning light's cause may be minor, but can also predict a potentially dangerous situation.