Check engine light

A check engine light or malfunction indicator lamp (MIL), is a <a href="/facts/Tell-tale_(automotive)/IQblfJMY">tell-tale</a> that a computerized engine-management system uses to indicate a malfunction or problem with the vehicle ranging from minor (such as a loose gas cap) to serious (worn spark plugs, engine problems or a faulty oil valve, etc.). Found on the instrument panel of most automobiles, it usually bears the legend engine, check engine, service engine soon, maintenance required, emiss 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 repairable fault, but service on the vehicle is strongly recommended as soon as possible to prevent future damage) and flashing (indicating a severe fault and an emergency that makes the vehicle unsafe to drive and it is strongly recommended that the vehicle gets mechanical attention straight away). When the MIL is lit, the <a href="/facts/Engine_control_unit/Q1uYhmyN">engine control unit</a> stores a fault code related to the malfunction, which can be retrieved—although in many models this requires the use of a <a href="/facts/On-board_diagnostics/rPmCA4NN">scan tool</a>. This warning light can indicate almost anything from a loose gas cap to a serious knock or fault in the engine.
In the United States, specific functions are required of the MIL by <a href="/facts/United_States_Environmental_Protection_Agency/ghI985SI">EPA</a> regulations.

Check engine light open-in-new

Check engine light