The sensor is mainly used in the engine is mainly used in electronic control system. The sensor can detect the physical quantities of the various states and convert the physical quantities into electricity for delivery. It is like a human sensory organ, the engine under all Sensor the conditions of the physical quantity of the correct detection, and enter the control computer circuit. Therefore, the sensor is to determine the engine electronic control system is a key component of good or bad;

  The speed sensor is usually mounted on a distributor or engine, which detects the corner of the crankshaft. Once the failure, will destroy the ignition system work, so that the engine can not work. Since most of the speed sensor is magnetic pulse, it can issue a weak electrical signal, the test can use a multimeter or oscilloscope;

    A good speed sensor with a multimeter AC voltage file to measure the rotation of the crankshaft, the output voltage should be in the range of 1.5 ~ 3.0V. If you suspect that the sensor internal wire contact is bad, you can set the multimeter in the resistance file and the sensor wire connected, and then shake the wire to see if the multimeter pointer swing, if the swing Fuel Rail Pressure Sensor is to prove the sensor internal wire contact is bad, should be excluded replacement; check method is removed Its wire plug, measured with a multimeter resistance file, the resistance should be in the range of 250 ~ 1500Ω;
   When the engine is running, connect the sensor wire, slowly increase the speed, and use the multimeter AC voltage file to measure, if the voltage value increases, then the sensor may be faulty; with a small rubber hammer gently tap into the air Tube, at the same time with a multimeter AC voltage file to measure. If the voltage indication value fluctuates, it indicates that the sensor is faulty; place the ignition switch in the (OFF) position, remove the sensor connector after 10s, place the ignition switch in the (ON) position, measure the signal on the wiring harness connector Output and the circuit between the DC voltage, the value should be consistent with the provisions, otherwise the line may be faulty;

   Water temperature sensor is to measure the temperature of the engine cooling water sensor, composed of thermistor, installed in the engine cooling waterway. When the cooling water temperature changes, its resistance changes. In the electronically controlled fuel injection system, this signal will be input to the electronic control unit, you can in accordance with the cooling water temperature correction Temperature Sensor of the amount of fuel injection. Therefore, the precision of the water temperature sensor has a certain impact on the fuel injection. When the mixture is too thick or too thin, you should first check the water temperature sensor, and then check the other sensors;

   The purpose of measuring the intake air temperature is to determine the density of the engine suction air and to correct the fuel injection amount in accordance with the change in the air density caused by the temperature change of the intake air. It is usually installed in the air flow meter or air grid after the intake manifold; structure and water temperature sensor is basically similar to the inspection can be used when the water temperature sensor inspection method. Under normal circumstances, when the temperature at 20 ℃, the resistance is about 2 ~ 3kΩ, 60 ℃, the resistance is about 0.4 ~ 0.7kΩ. If the measurement results do not meet the requirements, replace the sensor. Replace the air flow meter when the intake air temperature sensor installed in the air flow meter is damaged;

   Oxygen sensor Oxygen sensor has two types of heating and non-heating. For heating, it should check its heating resistance. Installed on the engine exhaust pipe. It is used to detect the concentration of oxygen molecules in the exhaust pipe and convert it into Voltage signal or resistance signal, so that the electronic control unit according to this signal to control the concentration of mixed gas; light with a multimeter Speed Sensor to measure the terminal of the heater between the two terminals of the resistance, the normal value should be 4 ~ 40kΩ The Otherwise it should replace its oxygen sensor;

 Visual inspection Remove the sensor from the exhaust pipe and check that the vent holes on the housing are clogged and the ceramic core is broken. If the damage should be replaced immediately; or remove the oxygen sensor harness connector, the voltmeter positive test rod directly connected with the oxygen sensor feedback voltage output. Start the engine, the use of a sudden step or relax the accelerator pedal method to change the concentration of the mixture, suddenly depress the accelerator pedal, the mixture is thickened, the feedback voltage should rise; suddenly relax, the mixed gas dilution voltage should be reduced, otherwise the sensor Failure, should be replaced;
  The knock sensor is mounted directly on Throttle Position Sensor the cylinder and is required to have high reliability or stability due to its direct temperature change or vibration on the engine block. Its maintenance tool 'multimeter';