What are the reasons for a motor vehicle failing to start?

[JuniperRose]

The reasons for a motor vehicle failing to start are: 1. Dead battery; 2. Expired battery lifespan; 3. Incorrect gear position—for automatic transmission vehicles, the gear must be in P (Park) or N (Neutral) when starting; 4. Manual transmission vehicles won't start if the clutch is not depressed; 5. Excessive carbon buildup in the vehicle. Solutions: 1. Refuel at reputable gas stations; 2. Frequently driving at high speeds can reduce carbon buildup; 3. Before starting the engine, turn the key to the ON position, then briefly return it before turning to the START position, allowing the computer to calculate water temperature and optimal air intake for smoother ignition; 4. Use antifreeze—adding water or low-quality antifreeze in extremely cold winter conditions can freeze the entire cooling system, crack the engine block, and render the water pump inoperable, preventing the vehicle from starting.