What is the problem when the car won't start?

[OSteven]

The reasons why a car won't start generally include: a dead battery or an empty fuel tank; incorrect gear position or a locked steering wheel preventing startup; automotive circuit or electronic failures, such as damaged spark plugs, blown fuses, or fuel pump malfunctions. Fuel quality issues, such as using poor-quality fuel that prevents the engine from operating properly, etc. Below are specific causes: Human operational reasons: dead battery, empty fuel tank, incorrect gear position. For automatic transmission cars, the gear must be in P (Park) or N (Neutral) to start; if it's in R (Reverse) or D (Drive), the car won't start. Some manual transmission cars won't start if the clutch isn't depressed. Vehicle usage reasons: improper fuel, lack of antifreeze, excessive carbon buildup. A dead battery could be due to leaving headlights on for a long time, causing power drain, or the battery's lifespan has expired. Installing xenon headlights, high-power audio systems, or DVD players can also lead to vehicle circuit failures.