Troubleshooting

P0101 Mass Air Fow Circuit Range/Performance Problem


CIRCUIT DESCRIPTION

DTC Detecting condition:

The mass air flow meter uses a platinum hot wire. The hot wire air flow meter consists of a platinum hot wire, thermistor and a control circuit installed in a plastic housing. The hot wire air flow meter works in principle that the hot wire and thermistor 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 air flow meter.

The circuit is constructed so that the platinum hot wire and thermistor can provide a bridge circuit with the power transistor, and controlled so that the potential of A and B can remain equal in order to maintain the set temperature.

If the ECM detects DTC P0100 it operates the fail-safe function, keeping the ignition timing and injection volume constantly and making it possible to drive the vehicle.

Step 1:

INSPECTION PROCEDURE

HINT: Read freeze frame data using LEXUS hand-held tester or OBD II scan tool, as freeze frame data records the engine conditions when the malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.