What does it mean when the CHECK light comes on in the car?

[SanEllie]

CHECK indicator light is the engine malfunction indicator lamp. Below are the specific reasons why the engine malfunction light may illuminate: 1. Irregular maintenance: Approximately 50% of engine-related faults are caused by poor maintenance. 2. Poor combustion: Suboptimal combustion conditions in the engine are a primary cause for the illumination of the engine malfunction light. In automotive design, to ensure the engine operates in good condition and maintains normal working lifespan, an oxygen sensor is installed to monitor the engine's combustion state. If combustion conditions deteriorate—such as excessive levels of hydrocarbons, carbon monoxide, or nitrogen oxides—it not only pollutes the environment but also leads to fuel wastage and excessive engine wear. 3. Engine knocking: The engine is equipped with a dedicated knock sensor to monitor knocking. Engine knocking indicates potential severe mechanical damage or significant power loss. Typically, knocking is categorized into perceptible and imperceptible knocking. In cases of imperceptible knocking, the engine control unit adjusts parameters to mitigate adverse effects. However, when imperceptible knocking exceeds the adjustable range of the engine control unit, the engine malfunction light will illuminate as a warning.