DTC P0102, P0103: Mass or Volume Air Flow Circuit Low Input; Mass or Volume Air Flow Circuit High Input: Description

The mass air flow meter sub-assembly is a sensor that measures the amount of air flowing through the throttle valve.

The hybrid vehicle control ECU uses this information to determine the fuel injection time and to provide the appropriate air fuel ratio.

Inside the mass air flow meter sub-assembly, there is a heated platinum wire which is exposed to the flow of intake air by applying a specific electrical current to the wire.

The flow of incoming air cools both the wire and an internal thermistor, affecting their resistance. To maintain a constant temperature value of the hot wire, current is applied to these components in the mass air flow meter sub-assembly. The voltage level is proportional to the airflow through the sensor, and the hybrid vehicle control ECU uses it to calculate the intake air volume.

The circuit is constructed so that the platinum hot wire and the temperature sensor create a bridge circuit, and the power transistor is controlled so that the potentials of A and B remain equal to maintain the predetermined temperature.

HINT:

When either of these DTCs are set, the hybrid vehicle control ECU enters fail-safe mode. During fail-safe mode, the ignition timing is calculated by the hybrid vehicle control ECU, according to the engine speed and throttle valve position. Fail-safe mode continues until a pass condition is detected.

Fig 1: Identifying Mass Air Flow Meter Sub Assembly Temperature Sensor

DTC No.	DTC Detection Condition	Trouble Area
P0102	Mass air flow meter voltage less than 0.2 V for 3 seconds (1 trip detection logic: Engine speed is less than 4000 rpm) (2 trip detection logic: Engine speed is 4000 rpm or more)	Open or short in mass air flow meter sub-assembly circuit Mass air flow meter sub-assembly EFI MAIN relay Hybrid vehicle control ECU
P0103	Mass air flow meter voltage more than 4.9 V for 3 seconds (1 trip detection logic: Engine speed is less than 4000 rpm) (2 trip detection logic: Engine speed is 4000 rpm or more)	Open or short in mass air flow meter sub-assembly circuit Mass air flow meter sub-assembly EFI MAIN relay Hybrid vehicle control ECU

HINT:

When any of these DTCs are set, check the air-flow rate by entering the following menus: Powertrain/Engine and ECT/Data List/MAF.

Mass Air Flow Rate (gm/s)	Malfunction
Approximately 0.0	Open in mass air flow meter sub-assembly power source circuit Open or short in VG circuit
271.0 or more	Open in EVG circuit