Circuit Description
WARNING: This page is about a different car, the 2002 Lexus ES 300. 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. If DTC P0101 is set, ECM will operate in fail-safe mode, keeping ignition timing and injection volume constant. DTC P0101 is set when throttle valve is fully closed, MAF sensor output is more than 2.2 volts, and Engine Coolant Temperature (ECT) sensor indicates more than 158°F (70°C) for 10 seconds or more at engine speed of less than 900 RPM.
DTC P0101 will also set when VTA sensor output is .63 volt or more, and MAF sensor output is less than 1.06 volts for 10 seconds or more at engine speed or 1500 RPM or more. Possible cause is faulty MAF sensor.