Since 1994, cars and trucks have been required to have an on-board diagnostics system to ensure proper emission-control system operation. If your vehicle shows any signs of having an emission problem, your “Check Engine” or “Service Engine Soon” light will glow. It is intended to inform the driver that a problem has been detected and vehicle service is needed.
It can be tempting to ignore this light. After all, your vehicle continues to drive in what seems like a normal fashion, and there seems to be no immediate need to take it in for service. A steady warning light indicates that something is amiss and the vehicle should be brought in for service as soon as is convenient. It is not an emergency situation, but should be addressed within a few days. However, a blinking warning light should be heeded immediately. A vehicle with this light flashing should be taken in for service at the earliest opportunity.
Possible causes of warning light activation include an overheating catalytic converter, an oxygen sensor malfunction, a fouled spark plug, a loose gas cap, or up to a hundred other causes. The glitches that activate this light are usually those which a driver would not detect. They can often lead to other problems if not addressed promptly, including fuel inefficiency, a shortened engine life, or expensive repairs. Your best bet is to take a reasoned response. It is not a cause for panic, but should not be ignored either.