Brief about Engine Check lights.
A check engine light or malfunction indicator lamp (MIL), is a tell-tale that a computerized engine-management system uses to indicate a malfunction. Found on the instrument panel of most automobiles, it usually bears the legend engine.
service engine soon, maintenance required, emmiss maint,or a pictogram of an engine—and when illuminated, it is typically an amber or red color.
Some older vehicles had a single indicator labeled "trouble" or "engine"; this was not an MIL, but an "idiot light" meant to indicate serious trouble with the engine (low oil pressure, overheating, or charging system problems) and an imminent breakdown. This usage of the "engine" light was discontinued in the mid-1980s, to prevent confusion with the MIL.
The MIL appeared in the early 80s along with computerized engine controls. Even the earliest systems, such as General Motors' CCC (Computer Command Control) system had self diagnosis functionality. When the computer detected a fault, it illuminated the MIL. Up until OBDII, on most cars the MIL could output codes, when two pins on the ALDL are jumped, the light would flash the codes, for instance (blink) (pause) (blink) (blink) for code 12. Some manufacturers, such as Honda, retained this feature even after OBDII. The MIL is commonly referred to today as the "check engine light" or the "service engine soon light"