For timely identification of problems associated with both the sensor itself and the operation of the air supply system. The most common symptoms of a malfunctioning temperature sensor are:
- The internal combustion engine does not start well at a low ambient temperature;
- The engine malfunctions at idle;
- A noticeable excess of fuel consumption;
- There are tangible interruptions in the operation of the motor;
- Turn on the light indication on the dashboard or display a message on the on-board computer.
The cause of such factors can be various malfunctions, both in the sensor itself and in the accompanying elements of the air supply system. Among the reasons for motorists are often identified:
- Short circuit in the sensor circuit;
- Oxidation of contacts, which makes a tangible correction for the measured value;
- Clogging of the sensitive element of the sensor - together with the sucked air, dust particles can circulate through the system, which settle in the area of the thermistor;
- Mechanical damage to the case or other auxiliary elements, which affects the accuracy of measurements;
- Open in the measuring circuit of the sensor.
Also note that the reason may be a clogged filter and poor system permeability. But to determine a specific malfunction, it is necessary to carry out diagnostics.
Diagnostics and replacement
To check the performance of the temperature sensor, you can use both simple methods available at home, and resort to the help of a service station. If you decide to diagnose the device yourself, you will need to get at least a simple multimeter. The verification process consists of the following steps:
- Disconnect the power cord from the intake air temperature sensor terminal block.
- Use a multimeter to measure the cold resistance of the sensor.
If the engine has just been turned off and you do not know the temperature, you can remove the sensor and forcibly cool it.
- Then, using a household hair dryer or, if the sensor is made of metal, heat the thermistor over the gas burner.
- Re-measure the resistance to electric current at the sensor terminals.
- Compare the measured results with the table for your sensor model
For example, consider a number of temperatures for a sensor from Lada Priora, shown in the table below:
Table: dependence of sensor resistance on temperature
As you can see, when measuring the resistance of a cold sensor, the temperature of which is 0 ° C, the multimeter will give 5.5 kΩ. If the sensor is heated to + 70 ° С, then the resistance will be about 450 ohms. Otherwise, the device is defective and cannot display the air temperature correctly and requires replacement.
To replace a failed temperature sensor, you need to follow a few simple steps. Unplug the power cord from the sensor and unscrew it from its seat.
Place a new temperature sensor in the seat and screw it tightly into the housing. Connect the connector to the terminal block - the device is ready for operation.