Genuine 2006 BMW X3 Mass Air Flow Sensor

2006 BMW X3 Mass Air Flow Sensor Parts Questions & Experts Answers

• Q:

  What is the function of the hot film mass air flow sensor in relation to the ECM in six cylinder engine on 2006 BMW X3?

  Posted by Noah J.

  A:

  The hot film mass air flow sensor transmits a flank voltage of about 0.5-4.5 V to the ECM as the intake air quantity. This air mass input signal is produced by using an electrically heated metal film, mounted inside the flow of the air current. DME main relay offers the operating voltage for the air flow sensor. The thin film of tin oxide is maintained at a specific temperature, the change in current required to hold the temperature constant gives the input signal; the air passing through the sensor causes the film to cool. When the air flow sensor does not transmit an output signal, then the other inputs that the ECM uses are throttle position and engine RPM. A blocked or defective air flow sensor can cause the MIL to turn on, and may result in other problems such as a car not being able to start when it is already warm, a car starts and die, or starts and runs only with the accelerator pedal floored.

  Answered by BMW Parts Specialist Blaine / Aug 23, 2025