Circuit Description
The mass airflow sensor uses a platinum hot wire. The hot wire airflow sensor consists of a platinum hot wire, temperature sensor and a control circuit installed in a plastic housing. The hot wire airflow sensor works on the principle that the hot wire and temperature sensor 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 platinum hot wire and temperature sensor 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 detected by open or short in mass airflow sensor circuit after more than 3 seconds at engine speed of 4000 RPM or less. DTC P0102 is detected by open or short in mass airflow sensor circuit after more than 3 seconds at engine speed of 4000 RPM or less. DTC P0103 is detected by open in mass airflow sensor circuit after more than 3 seconds (EVG circuit) or short in mass airflow sensor circuit with more than 3 seconds (B+ circuit). See Fig 1 and Fig 2 . Possible causes are:
- Open or short in MAF circuit.
- Faulty MAF sensor.
- Faulty ECM.