To detect a valve sensor malfunction, first remove the connector plug of the sensor, and then use a multimeter to measure the resistance between the sensor's signal output terminal and ground terminal, in order to detect the specific fault location and solve the problem accordingly. A sensor is a device that can convert a quality signal into a measurable electrical signal output. Damaged valve position sensors can cause engine shaking and unstable idle speed. Because the throttle position sensor is a signal that detects the throttle opening, the engine computer will adjust the fuel injection quantity and ignition time based on the throttle opening. If the throttle position sensor malfunctions, it will cause the engine computer to not receive the signal correctly, resulting in the engine not being able to start. There are three common faults of the throttle position sensor. One is a short circuit or short circuit in the idle switch, the other is improper installation and adjustment of the throttle position sensor, and the other is poor contact of the sliding contact of the limit variable resistor, causing intermittent interruption of the throttle sensor output signal