The fault of the air flow sensor has a great impact, so how to detect it?

“Due to the imbalance of the mixing ratio, the combustion of the engine is not normal, and the engine speed will be unstable or the power will be poor. When the plug of the air flow sensor is unplugged, the Electronic control unit will immediately enter the fail-safe function if it cannot detect the intake signal, and replace the air flow sensor signal with the signal of the throttle position sensor, so that the engine continues to work with the substitute value. Unplug the air flow sensor plug and the fault disappears, which means that the signal is incorrect before the plug is pulled, and the signal is correct after the plug is pulled, so the fault disappears.

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A faulty air flow sensor can lead to unstable engine idle speed and poor acceleration. This article describes how to detect air flow sensors.

1) When the engine is running, unplug the air flow sensor. If the fault disappears, it means that the air flow sensor signal is deviated and not damaged. The Electronic control unit has been performing fuel injection control according to the deviated error signal.

Bearing Removal Tool

Due to the imbalance of the mixing ratio, the combustion of the engine is not normal, and the engine speed will be unstable or the power will be poor. When the plug of the air flow sensor is unplugged, the electronic control unit will immediately enter the fail-safe function if it cannot detect the intake signal, and replace the air flow sensor signal with the signal of the throttle position sensor, so that the engine continues to work with the substitute value. Unplug the air flow sensor plug and the fault disappears, which means that the signal is incorrect before the plug is pulled, and the signal is correct after the plug is pulled, so the fault disappears.

2) Measure the dynamic signal voltage at the signal end of the plug. Under idle speed conditions, the standard voltage is 0.8-1.4V; when accelerating to full load, the voltage signal can be close to 4V. If it is not in this range, the air flow sensor itself may be damaged. In some cases, it is also caused by dirt, and it can be cleaned.

3) When the engine is running, unplug the air flow sensor. If the fault persists, it means that the main reason is that the air flow sensor is damaged (the related Circuit will also cause the fault); the engine control unit cannot receive the air flow sensor signal, and the electrical The control unit confirms that the signal of the air flow sensor is bad, enters the fail-safe function, and stores the fault code in the memory at the same time.

4) When the engine is running, unplug the air flow sensor, the fault phenomenon changes slightly. It means that the air flow sensor is in good condition. Before unplugging the air flow sensor plug, the electronic control unit controls the signal according to the air flow sensor signal, the fuel injection amount is accurate, and the engine is in good condition; The unit is controlled according to the signal of the throttle position sensor, the fuel injection amount is slightly different, and the engine working condition is relatively poor.