What does a yellow engine light mean?

[LaAbigail]

A yellow engine light indicates a fault in the engine, which can be caused by: 1. Poor quality gasoline leading to incomplete combustion of the air-fuel mixture in the cylinders, resulting in excessive carbon deposits, clogged fuel lines, and potential corrosion of components, affecting the normal concentration of the air-fuel mixture and causing engine malfunction accompanied by shaking; 2. Damaged or loose oxygen sensor or sensor connector, leading to an overly lean or rich air-fuel mixture and engine malfunction; 3. If the air flow sensor or its circuit malfunctions, the engine control unit will not receive accurate intake air volume signals, preventing proper fuel quantity adjustment, thereby causing an overly lean or rich air-fuel mixture, engine malfunction, and sometimes triggering the engine warning light; 4. Spark plug carbon deposits can cause poor engine performance, resulting in difficulties starting, unstable idling, poor acceleration, backfiring during rapid acceleration, excessive exhaust emissions, increased fuel consumption, and other abnormal symptoms.