Circuit Description
WARNING: This page is about a different car, the 2002 Lexus GS 430. However, it is still accessible from the selected car via links, so may be relevant.
MAF sensor uses a platinum hot wire maintained at a constant temperature. Airflow past sensor affects temperature and current flow through sensor. DTC P0101 is set when throttle valve is fully closed, MAF sensor output is more than 2.2 volts, and engine is at operating temperature for 10 seconds or more at engine speed of 900 RPM or less.
DTC P0101 will also set when Throttle Position (TP) sensor output is .63 volt or more, and MAF sensor output is less than one volt for 6 seconds or more at engine speed of 1500 RPM or more. Possible cause is; faulty MAF sensor.