Troubleshooting
P0101 - Mass Air Flow Circuit Range/Performance ProblemCIRCUIT DESCRIPTION
DTC Detecting Condition:
The air flow meter uses a platinum hot wire. The hot wire air flow meter consists of a platinum hot wire, temperature sensor and a control circuit installed in a plastic housing. The hot wire air flow meter 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 air flow meter.
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.
HINT: After confirming DTC P0100/31, use the hand-held tester to confirm the airflow ratio from CURRENT DATA.
Wiring Diagram:
Step 1:
INSPECTION PROCEDURE
HINT: Read freeze frame data using TOYOTA hand-held tester or OBDII scan tool. Because freeze frame 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.