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What is a Mass Air Flow Sensor?

The mass air flow sensor, installed at the intake system of the electronic control system, measures the amount of air flow (i.e., the amount of air sucked into the engine).
Air sucked into the engine passes through the air cleaner and then enters the mass air flow sensor. The mass and temperature of the air are measured by the sensor, and the measurement information is transmitted to the engine control unit (ECU). After passing through the mass air flow sensor, the air flows through the throttle valve and is sucked into the combustion chambers.

The two following mounting types are available for the mass air flow sensor.

1. For the "Assembly Type" mass air flow sensor, the sensor and the air flow sensor body are integrated.

2. For the "Slot-in Type" mass air flow sensor, the sensor is directly inserted and mounted to the air flow sensor body, air filter case, and intake pipes.

Typical Symptoms in Case of Failure

Symptoms in case of failure

• The engine almost stalls when braking to a stop
• The idle speed becomes low
• The idle speed occasionally decreases
• The engine almost stalls when warming up and restarting

If the malfunction indicator light lights up after replacing the mass air flow sensor, the learning value needs to be initialized.