Why is the car's warning light constantly on?

[DiLucas]

The reasons for the car's warning light being on include faults in the water temperature sensor, crankshaft sensor, oxygen sensor, spark plugs, ignition coil, etc. When the engine warning light comes on, it can be categorized into three scenarios: 1. The car cannot start, which might be due to a fuel pump or ignition component failure—immediate assistance should be sought; 2. The warning light is on, but there are no noticeable abnormalities while driving—this could simply be a sensor malfunction, allowing for continued driving at low to moderate speeds with caution; 3. The engine warning light is on, the vehicle can still be driven, but exhibits severe shaking, lack of power during acceleration, etc.—in such cases, the car should be stopped and rescue services called.