The mass air flow sensor on the VAZ-2123 engine is located between the air filter housing and the air supply hose to the throttle assembly.
The sensor uses a thermoanemometric flow measurement method, which is based on the removal of heat by the moving air flow.
When a current-heated thermistor (transducer of the thermoanemometer) is placed in a moving air medium, the removal of heat by the air flow is the main factor affecting the heat transfer of the thermistor.
The resistance of the thermistor changes due to cooling by the flow, as a result of which the resistor acts as an air flow sensor.
If the mass air flow sensor or its circuits fail, the «CHECK ENGINE» lamp lights up.
In this case, the controller calculates the mass air flow value from the crankshaft speed and the throttle position.
The output signal of the air temperature sensor connected to the controller is a direct current voltage in the range of 0.2…4.8 V, the value of which depends on the temperature of the air passing through the sensor.
If a fault occurs in the air temperature sensor circuit, the controller stores its code in its memory and switches on the warning lamp.
In this case, the controller replaces the sensor readings with a fixed air temperature value (20 °C).
Removal of the mass air flow sensor
- Disconnect the negative terminal of the battery.
- Using a Phillips screwdriver, loosen the clamp securing the air hose to the mass air flow sensor.
- Move aside the yellow stop of the retainer of the engine management system wiring connector to the mass air flow sensor.
- Press the retainer and disconnect the wiring connector from the sensor.
- Using a 10 spanner, unscrew the two bolts securing the mass air flow sensor.
- Remove the mass air flow sensor from the air filter housing.
Marking of the mass air flow sensor.
Installation of the mass air flow sensor
- Before installing the sensor, fit the sealing sleeve onto it as far as it will go. The absence of the sealing sleeve can lead to engine malfunction.
- Install the sensor on the air filter and secure it with two bolts. Bolt tightening torque: 3.0–5.0 N·m.
- Connect the intake pipe hose to the sensor and secure it with a clamp. Clamp screw tightening torque: 2.2–2.8 N·m.
- Connect the wiring harness connector to the sensor and latch the retainer.
Important! When working with the sensor, take care:
- Do not allow foreign objects to enter the interior of the sensor.
- Damage to the sensor will lead to malfunction of the engine management system.
- It is prohibited to remove the sensing element from the sensor housing, as this may change its characteristics.
Table of dependence of the air temperature sensor resistance on the temperature of the intake air
