What causes the engine light to turn yellow?

[CarlosDella]

When the engine light turns yellow, it indicates that there is a fault in the engine, which could be either a false alarm or a genuine issue. The reasons for the engine fault light turning on are as follows: 1. Dirty engine cylinders with carbon deposits. Over time, some carbon deposits will inevitably accumulate inside the engine. These deposits can alter the engine's design parameters and are inherently unstable, trapping heat. The trapped heat can cause uncontrolled ignition, leading to engine knocking. 2. The primary reason for the engine fault light turning on is poor combustion in the engine. Oxygen sensors are installed in the engine to monitor its combustion state. If the combustion state is poor, the engine fault light will illuminate.