Contents: General information ⇓ Troubleshooting Guide ⇓
General information
The hot-wire air flow sensor consists of a heat-sensitive film sensor, a housing and a measuring channel (hybrid sensor element). The principle of measuring air mass flow by this type of sensor is based on the fact that a change in the air flow passing through the sensor causes a change in the amount of heat transferred from the surface of the film sensor element (film) to the air flow. The air flow sensor generates pulses by successively opening and closing the circuit through which 5 V power is supplied from the electronic engine control unit.
The intake manifold air temperature sensor, located in the intake air hose, is a resistive type sensor that is sensitive to changes in air temperature. Based on the intake manifold air temperature data, the engine control unit determines the required fuel supply.
- Intake air temperature sensor: Resistance (at 20°C): 2.33-2.97 kOhm
Troubleshooting Guide
1. If the engine stalls occasionally, start the engine and try shaking the air flow sensor wiring harness. If the engine stalls after this, check for poor contact in the air flow sensor connector.
2. If the air flow sensor output signal is registered to be different from zero when the ignition is turned on (key position "ON") and the engine is not running, then the air flow sensor or the engine control unit may be faulty.
3. If the engine is idling (even if the air flow sensor output voltage is not normal), the cause is usually one of the following faults:
- a) Violation of the normal flow of air through the air flow sensor, disconnection of the air duct or clogging of the replaceable air filter element.
- b) Incomplete combustion of the working mixture in the cylinder, malfunction of spark plugs, ignition coil, injectors and violation of compression.
Air flow sensor output voltage:
- Nominal value:
- Idle: 0.5 V
- 2000 rpm: 1.0 V
4. Even if there are no signs of a malfunction of the air flow sensor, check that it is installed correctly (air flow direction).
Note:
- On a new car (mileage less than 500 km), the air flow sensor readings will be higher than the actual air flow by approximately 10%.
- It is recommended to use an accurate digital voltmeter when performing checks.
- Before starting the check, it is necessary to warm up the engine so that the coolant temperature reaches 80-90°C.
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