Circuit Description
The mass airflow sensor uses a platinum hot wire. The hot wire airflow sensor consists of a wire element (cold wire), and a control circuit installed in a plastic housing. The hot wire airflow sensor works on the principle that the hot wire and wire element (cold wire) located in the intake air bypass of the housing, detect any changes in the intake air temperature. The hot wire is maintained at the set temperature by controlling the current flow through the hot wire. This current flow is then measured as the output voltage of the mass airflow sensor. The circuit is constructed so that the wire element (cold wire) and wire element (hot wire) provide a bridge circuit with the power transistor controlled so that the potential of "A" and "B" remains equal to maintain the set temperature. DTC P0100 is set when an open or short is detected in mass airflow sensor circuit for more than 3 seconds with engine speed at 4000 RPM or less. DTC P0102 is set when an open is detected in mass airflow sensor circuit for more than 3 seconds at engine speed at 4000 RPM or less. DTC P0103 is set when a short is detected in mass airflow sensor circuit for more than 3 seconds with engine speed at 4000 RPM or less. See Fig 1 and Fig 2 . Possible causes are:
- MAF sensor circuit is open or shorted.
- Defective MAF sensor.
- Defective ECM.