The working principle of oil level sensors is usually based on some physical or electrical characteristics. For example, in a floating ball sensor, when the oil level rises, the floating ball also rises, triggering an internal switch and sending out a signal; In resistive sensors, changes in oil level cause changes in liquid resistance, which are transmitted through circuits. Capacitive sensors determine oil level by measuring changes in capacitance, making them suitable for high-precision applications. Ultrasonic sensors use the reflection of sound waves to measure oil levels, which has the advantage of non-contact and is suitable for use in harsh environments.