What causes the engine yellow warning light to come on?

[SanPreston]

There are many reasons for the engine fault yellow warning light to illuminate, with the following being the most common: 1. The oxygen sensor connector is damaged or loose, causing the air-fuel mixture to be too lean or too rich. 2. Poor quality or substandard gasoline leads to insufficient combustion of the air-fuel mixture during engine operation. 3. Poor engine maintenance, such as issues with spark plugs, ignition coils, fuel pumps, or clogged fuel lines, resulting in poor combustion of the engine's air-fuel mixture. 4. The engine requires air for combustion; a dirty air filter that hasn't been cleaned regularly can affect the engine's air intake, leading to long-term clogging and potentially causing the engine fault light to illuminate.