Automotive oil pressure sensor function
The main function of the automobile oil pressure sensor is to detect the oil pressure and issue an alarm when the pressure is insufficient . The oil pressure sensor is installed on the main oil pipeline of the engine, detects the oil pressure through the pressure measuring device, and converts these pressure signals into electrical signals, which are transmitted to the signal processing circuit. When the oil pressure drops below the preset safe value, the oil indicator light on the dashboard will light up to alert the driver to .
Working principle
There is a sliding resistance inside the oil pressure sensor, and the oil pressure change will push the sliding resistance potentiometer to move, and then change the current of the oil pressure gauge, so that the pointer position changes. At the same time, the signal is transmitted to the oil pressure indicator through the signal line, and the ratio of the current passed by the two coils in the indicator is changed, thus indicating the oil pressure of the starting motor . The sensor is usually composed of a thick film pressure sensor chip, a signal processing circuit, a housing, a fixed circuit board device and two leads. The signal processing circuit includes power supply circuit, sensor compensation circuit, zeroing circuit, voltage amplification circuit, current amplification circuit, filter circuit and alarm circuit .
Installation position
The oil pressure sensor is generally installed on the main oil pipeline of the engine, and sometimes on the oil filter seat. The sensor is composed of a contact, a spring, a diaphragm and a diaphragm. When there is no oil pressure, the spring pushes the diaphragm to close the contact; When the pressure reaches the specified value, the diaphragm overcomes the spring force and breaks the contact .
The symptoms of automotive oil pressure sensor failure mainly include the following aspects :
: When the oil pressure sensor is damaged, the oil pressure indicator will continue to light, regardless of the actual oil pressure, which may mislead the driver to believe that the engine oil pressure is abnormal.
Steady on : A light on an engine failure light (also known as an MIL or check engine light) usually means a fault has been detected by the vehicle's electronic control system. The oil pressure sensor failure is also one of the reasons for the light to be on.
Abnormal oil pressure value display : In the idling state of the vehicle, if the oil pressure sensor fails, the oil pressure value displayed on the dashboard may be abnormal, such as always displayed as a fixed value (such as 0.99) or abnormal fluctuation range.
Fault code P01CA appears : When the vehicle diagnostic system detects that the oil pressure sensor voltage is out of the normal range, the corresponding fault code, such as P01CA, will be recorded and displayed. This trouble code directly indicates a problem with the oil pressure sensor.
Causes of oil pressure sensor failure may include :
The sensor itself is of poor quality : manufacturing defects or aging lead to inaccurate or damaged detection.
Line problems : Short circuit, open circuit or poor contact can affect signal transmission.
abnormal oil pressure : too high or too low oil pressure will bring greater pressure to the sensor.
Sludge contamination : Sludge from inside the engine can clog or contaminate sensors.
incorrect installation position : the deviation of the installation position will affect the detection accuracy of the sensor.
other parts of the engine malfunction : such as filter blockage, insufficient oil, etc.
Power supply voltage instability : voltage fluctuation will interfere with the normal operation of the sensor.
Internal short circuit caused by sensor entering liquid or oil .
Detection and treatment methods :
Use the diagnostic instrument : read the fault code by connecting the OBDII diagnostic interface, e.g. P0520 (oil pressure sensor circuit fault).
Check the cable connections to the sensor : ensure that the cable connections are not corroded, broken, or loose.
Measuring the output voltage of the sensor : Use a multimeter to measure the output voltage of the sensor and ensure that it outputs the correct voltage under different pressures.
Mechanical pressure gauge comparison test : Remove the electronic oil pressure sensor and install the mechanical pressure gauge for comparison test to determine whether the sensor is invalid.
Replace the sensor : If the sensor is confirmed to be invalid, replace it with a new sensor that matches the original car.
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