1. Use a voltmeter: First, you need to use a voltmeter to detect the voltage of the battery. If the voltage is lower than 12V, the battery may need to be replaced. Then, you need to check whether the resistance value of the sensor meets the specification. Generally, it should be between 1 and 2 ohms. If the resistance value exceeds this range, the sensor may be damaged.
2. Use a multimeter: First, disconnect the negative electrode connection wire of the battery. Then, turn on the resistance measurement function of the multimeter and set a higher resistance range between the red and black test poles. Next, touch the two contacts of the sensor with a test pen. If the circuit is unobstructed, the resistance value between the red and black test poles of the multimeter should be 0 ohms.
3. Use an oscilloscope: First, you need to remove a section of wire from the negative electrode sensor of the battery and connect one end of it to the probe of the oscilloscope. Then, you can start the engine and observe the working status of the sensor by modifying the electrical interface of the car. If the oscilloscope can capture the signal normally, it means that the sensor is working properly.