What are the reasons why the ignition device cannot start the engine?

[VonCharles]

The reasons why the ignition device cannot start the engine are as follows: Battery cannot hold charge: The vehicle runs out of power after being parked for just 1 day. Besides the sulfation of the battery plates (which prevents charging), it may be due to leakage in the vehicle's wiring harness. Coolant temperature sensor short circuit: If the engine fails to start after multiple attempts and the spark plug electrodes are very clean, it may be due to a short circuit in the coolant temperature sensor. Fuel filter clogged: While driving, the vehicle's speed suddenly drops and continues to decrease until the engine stalls. After stalling, the engine can be restarted, but the speed is even lower, and the vehicle cannot maintain operation, eventually stalling again and failing to restart. Anti-theft device lock: When the anti-theft device is locked, the steering wheel cannot be turned, the anti-theft indicator light on the dashboard is illuminated, and the control unit interrupts fuel supply control but not ignition. The engine cannot start, indicating that the steering wheel and ignition switch are locked by the central control. By forcefully turning the steering wheel, the anti-theft system will automatically unlock, allowing normal startup.