The yellow light of the engine fault light indicates that the engine has a fault. The following is the relevant content: 1. Cause of the fault: There is a problem with the gasoline added or there is too much carbon deposit in the engine, which leads to poor engine combustion. Problems such as the fuel injector or intake valve blockage and carbon deposits will cause the fault light to alarm. 2. Automobile oxygen sensor: Automobile oxygen sensor is a key feedback sensor in the electronic fuel injection engine control system. It is a key part for controlling automobile exhaust emissions, reducing automobile pollution to the environment, and improving the fuel combustion quality of automobile engines. Oxygen sensors are installed on the engine exhaust pipe.