Your Check Engine Light might be turning On and Off or flickering (not flashing) for several reasons. It could be a loose or damaged wire or connection in the onboard diagnostic system. Or, a minor fault that only occurs under certain conditions, like when accelerating. The Check Engine Light could also be going on and off due to a bad sensor, spark plug, or filter.
To be clear, the Check Engine Light turning on and off seemingly at random,only under specific conditions, or flickering is different from a flashing light that goes on and off similar to how a turn signal flashes or blinks.
A constant flashing or blinking light indicates a more serious problem. Check out our article “What Your Check Engine Light Means & 13 Possible Reasons It’s On” for more information on flashing lights, on and off lights, and what your car is trying to tell you.