CEL meaning in Space Science ?

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, check 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.

The light generally has two stages: steady (indicating a minor fault) and flashing (indicating a severe fault). When the MIL is lit, the engine control unit stores a fault code related to the malfunction, which can be retrieved—although in many models this requires the use of a scan tool. This warning light can indicate almost anything from a loose gas cap to a serious knock in the engine.

In the United States, specific functions are required of the MIL by EPA regulations.