LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Toyota >> 2007 >> Prius Base >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Control System >> SFI System >> DTC P0100 Mass or Volume Air Flow Circuit; DTC P0102 Mass or Volume Air Flow Circuit Low Input; DTC P0103 Mass or Volume Air Flow Circuit High Input >> Description
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC P0100 Mass or Volume Air Flow Circuit; DTC P0102 Mass or Volume Air Flow Circuit Low Input; DTC P0103 Mass or Volume Air Flow Circuit High Input: Description

The MAF (Mass Air Flow) meter measures the amount of air flowing through the throttle valve. The ECM uses this information to determine the fuel injection time and provides a proper air-fuel ratio. Inside the MAF meter, there is a heated platinum wire exposed to the flow of intake air.

By applying a specific current to the wire, the ECM heats this wire to a given temperature. The flow of incoming air cools the wire and an internal thermistor, affecting their resistance. To maintain a constant current value, the ECM varies the voltage applied to these components in the MAF meter. The voltage level is proportional to the air flowing through the sensor. The ECM interprets this voltage as the intake air amount.

The circuit is constructed so that the platinum hot wire and temperature sensor provide a bridge circuit, and the power transistor is controlled so that the potential of A and B remains equal to maintain the set temperature.

Fig 1: Volume Air Flow - Circuit Diagram
G05188633Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
DTC DETECTION CONDITION

DTC No. DTC Detection Condition Trouble Area
P0100 When the mass air flow meter circuit has an open or a short for more than 3 seconds
  • Open or short in mass air flow meter circuit
  • Mass air flow meter
  • ECM
P0102 When the mass air flow meter circuit has an open for more than 3 seconds
  • Open in mass air flow meter circuit
  • Mass air flow meter
  • ECM
P0103 When the mass air flow meter circuit has a short for more than 3 seconds
  • Short in mass air flow meter circuit
  • Mass air flow meter
  • ECM

HINT:

After confirming DTC P0100, P0102 or P0103, confirm the mass airflow ratio in DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY.

DATA LIST

Air Flow Rate (g/sec.) Malfunction
Approximately 0.0
  • Mass air flow meter power source circuit open
  • VG circuit open or shorted
271.0 or more
  • E2G circuit open