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Home >> Toyota >> 2008 >> FJ Cruiser RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 144 (Engine Control System (2UZ-FE)) >> SFI System >> DTC P0100 Mass Air Flow Circuit Malfunction: DTC P0102 Mass Air Flow Circuit Low: DTC P0103 Mass Air Flow Circuit High >> Description

DTC P0100 Mass Air Flow Circuit Malfunction: DTC P0102 Mass Air Flow Circuit Low: DTC P0103 Mass Air Flow Circuit High: Description

WARNING: This page is about a different car, the 2007 Toyota Land Cruiser. However, it is still accessible from the selected car via links, so may be relevant.

The Mass Air Flow (MAF) meter measures the amount of air flowing through the throttle valve. The ECM uses this information to determine the fuel injection time and provide 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 flow 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, with the power transistor controlled so that the potential of A and B remains equal to maintain the set temperature.

Fig 1: Temperature Sensor Operation Diagram With Bridge Circuit
G05196621Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
DTC TROUBLE DETECTION CONDITION

DTC No. DTC Detection Condition Trouble Area
P0100  Open or short in Mass Air Flow (MAF) meter circuit with more than 3 seconds at engine speed 4,000 rpm or less (1 trip detection logic)
  • Open or short in Mass Air Flow (MAF) meter circuit
  • Mass Air Flow (MAF) meter
  • ECM
P0102  Open or short in MAF meter circuit with more than 3 seconds at engine speed 4,000 rpm or less (1 trip detection logic)
  • Open in MAF meter circuit
  • Short in ground circuit
  • MAF meter
  • ECM
P0103  Open to EVG in MAF meter circuit with more than 3 seconds at engine speed 4,000 rpm or less Short to +B in MAF meter circuit with more than 3 seconds at engine speed 4,000 rpm or less (1 trip detection logic)
  • Short in MAF meter circuit (+B circuit)
  • MAF meter
  • ECM

HINT:

After confirming DTC P0100, P0102 or P0103, use the intelligent tester to confirm the MAF (to reach the MAF menu: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY).

MASS AIR FLOW RATE CHART

Mass Air Flow Rate (g/sec.) Malfunction
Approximately 0.0
  • MAF meter power source circuit open
  • VG circuit open or short
MASS AIR FLOW RATE CHART

Mass Air Flow Rate (g/sec.) Malfunction
271.0 or more E2G circuit open