A “check engine” light or a “service engine soon” light can be caused by many things. The most important thing to know is this. If the light comes on and starts to flash or blink on and off, turn off the engine right away and have your car towed to your mechanic to have it checked. A flashing check engine light is letting you know that more damage WILL happen if you keep driving it. A light that has just come on, could mean anything, from forgetting to tighten your gas cap completely, to a loose hose. The problem with not having it checked out even if you’re not noticing anything wrong, is if you have a worse problem, you will have no way of knowing because you ignored the light earlier.