Mass Air Flow Sensor Fail: How To Diagnose And Fix

The mass air flow sensor is used to measure the amount of air entering the engine and is essential for determining the air-fuel mixture in the engine. Based on this information, the engine control unit calculates the appropriate amount of fuel to be injected. Ideally, the fuel-air mixture is stoichiometric, meaning 1:14.7 (14.7 kg of air is needed to burn 1 kg of fuel, equivalent to 32.4 pounds of air to burn 2.2 pounds of fuel).

Symptoms of Mass Air Flow Sensor Fail

• Reduced engine performance;
• Increased fuel consumption;
• Rough engine running;
• Engine speed fluctuations;
• Engine stalling;

A faulty mass air flow sensor exhibits some characteristic symptoms. These typically include significantly reduced engine performance and increased fuel consumption, as well as rough engine running (especially at low engine speeds and idle). However, these symptoms are not necessarily related to the mass air flow sensor and can also be caused by a faulty oxygen sensor or ignition coil.

In rare cases, the engine may suddenly shut off. This often occurs when approaching an intersection or traffic light and can become dangerous, as the power steering and brake assist also fail simultaneously. Such engine stalling can also be caused by a faulty crankshaft sensor.

Causes of Mass Air Flow Sensor Fail

The most common cause of problems with the mass air flow sensor is not replacing the air filter. If the air filter is not replaced, dirt accumulates on the sensor unit of the mass air flow sensor, leading to its damage or malfunction. High-performance air filters, in particular, are harmful to the mass air flow sensor and should be avoided.

See Also:

• How To Diagnose Bad Crankshaft Position Sensor;