What does it mean when the engine warning light stays on?

[Anderson]

There are several reasons why the engine warning light may stay on: 1. Issues that can trigger the engine warning light. Fuel quality problems, where poor gasoline quality leads to incomplete combustion of the air-fuel mixture in the cylinders, causing the light to illuminate. Intake system issues, such as a clogged air filter in the car, can also trigger the engine warning light if severe. 2. Faulty spark plugs, ignition coils, fuel pump, or clogged fuel lines can all cause poor combustion of the air-fuel mixture in the engine. Poor combustion leads to engine carbon buildup or knocking issues, which are detected by the engine's oxygen sensors. The ECU then triggers the warning light as an alert. 3. Excessive carbon buildup can make ignition difficult, causing the ignition coil to fail due to reverse breakdown. This leads to poor ignition, incomplete combustion, increased pollution, and ultimately, the engine warning light coming on.