The regular failure performance of the eight major sensors of the car!

Automotive sensors are very important components. If they are damaged, the corresponding components will not work properly. Then, the guest bacteria will sort out some of the failure behaviors of the eight conventional sensors this time. Then you can judge by these performances in the future. Which sensor is the problem?

 

The function of each sensor and the way of failure performance-

Air flow sensor

At present, there are mainly two types of hot-wire air flow sensors and hot-film air flow sensors, which are generally installed between an air filter and a throttle valve.

Role: Measure the air intake of the engine, and input the signal into the ECU as the main control signal for fuel injection and ignition control.

Failure method: After the air flow meter fails, the car computer (ECU) cannot detect the true intake of air, resulting in an imbalance of the mixture, which results in unstable engine idling, weak driving and black smoke, and sometimes shifts gears. Flameout

Intake pressure sensor

The intake air pressure sensor is referred to as MAP sub-resistive intake air pressure sensor and capacitive intake air pressure sensor. It is installed on the intake manifold and is usually integrated with the intake air temperature sensor.

Function: Detect the absolute pressure of the intake manifold, then convert it into a voltage signal and send it to the ECU. The ECU controls the basic fuel injection amount based on the voltage of this signal.

Failure mode: The fuel injection amount cannot be controlled normally, causing the mixture to be too rich or too lean, which will cause the engine to run abnormally, and the engine will also suffer from idling instability, often stalls, and cannot start even when the fuel consumption soars or is serious.

Throttle position sensor

Throttle position sensor is divided into switch contact type throttle position sensor, linear variable resistance throttle position sensor, and comprehensive throttle position sensor. The throttle position sensor is installed on the throttle and is used to detect the opening degree of the throttle.

Role: The main function of the throttle sensor is to feedback the opening of the throttle, so as to control the fuel injection amount during acceleration.

Failure mode: The engine idling abnormally (such as too high or too low idling, unstable idling, easy to stall at idle speed) or abnormal acceleration of the engine (the engine trembles during acceleration, retarded acceleration response, etc.), sometimes it can also cause the engine to be running. Intermittent jitter appears.

Camshaft position sensor

The camshaft position sensor is used to detect the angular position of the camshaft. The engine control module (ECU) uses this signal to determine the cylinder sequence of the engine.

Role: Detect the camshaft position, determine the top dead center of the compression stroke of a cylinder, control the sequential injection and ignition

Failure mode: When the camshaft position sensor fails, the output power of the engine will decrease. There will be ignition failure, it is difficult to add the gas pedal, the car will tremble, and the fault light is always on, and it will turn off when the car is hot.

Crankshaft position sensor

Crankshaft position sensor (CKP) is one of the most important sensors in the centralized engine control system. It is an indispensable signal source for confirming the crankshaft position and the engine speed.

Function: The engine control module (ECU) uses this signal to control the fuel injection quantity, fuel injection timing, ignition timing (ignition advance angle), ignition coil charging closing angle, idle speed and electric gasoline pump operation.

Failure method: The crankshaft position sensor is broken, and the crank angle cannot be confirmed. The engine computer cannot receive the signal from the crankshaft position sensor. In order to protect the engine, it will not ignite or fuel injection. The symptom of the car is that there is no high-voltage power. , Can’t hit the car without fuel injection.

Oxygen Sensor

Role: The fundamental role of the oxygen sensor is to detect the oxygen concentration in the exhaust gas, and then the ECU (engine system control computer) will use the oxygen concentration signal provided by the oxygen sensor to determine the combustion status of the engine (front oxygen) or the efficiency of the catalyst (Post oxygen). There are zirconia type and titanium oxide type

Failure method: If the oxygen sensor fails, the engine performance is poor, the lambda adjustment is fixed, the idle speed is unstable, the emission value is abnormal, the fuel consumption increases, and the spark plug deposits carbon. Oxygen sensor poisoning is a frequent and difficult-to-control failure, especially for cars that often use leaded gasoline.

Water temperature sensor

The water temperature sensor is actually a semiconductor thermistor. The lower the temperature, the larger the resistance. On the other hand, the smaller the resistance, the more it is installed on the water jacket of the engine block or cylinder head, and it is in direct contact with the cooling water.

Failure mode: When the water temperature sensor fails (usually poor contact, short circuit, open circuit, but most of them are poor contact), the phenomenon shown is ON, the engine fault light is always on, the water temperature always shows the maximum 120 degrees Celsius, the engine Torque is limited and weak. The detected fault code is P003D. If the water temperature sensor fails, the car will have difficulty starting the car cold, the fuel will not be normal, the acceleration will be weak, and the rapid acceleration will have a temper.

Knock sensor

Role: The knock sensor is used to detect whether knock occurs in the combustion process of the engine and sends the knock signal to the engine control computer as an important reference signal for correcting the ignition advance angle.

Failure mode: When the knock sensor fails, the engine will deflagrate, the ignition timing will be out of alignment, high fuel consumption, reduced power, difficult starting, and rough engine work.