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Home >> Lexus >> 2006 >> RX 330 AWD >> Repair and Diagnosis >> Engine Performance >> Remove, Overhaul & Install >> Engine Control System (3MZ-FE) >> 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
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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 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, changing 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: Identifying Mass Air Flow Circuit
G04087152Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
DTC REFERENCE

DTC No. DTC Detection Condition Trouble Area
P0100 When MAF meter circuit has an open or a short for more than 3 seconds under 4,000 rpm engine speed
  • Open or short in MAF meter circuit
  • MAF meter
  • ECM
P0102 When MAF meter circuit has an open for more than 3 seconds under 4,000 rpm engine speed
  • Open or short in MAF meter circuit
  • MAF meter
  • ECM
P0103 When MAF meter circuit has a short for more than 3 seconds under 4,000 rpm engine speed
  • Open or short in MAF meter circuit
  • MAF meter
  • ECM

HINT:

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

DATA LIST REFERENCE CHART

Air Flow Value (gm/s) Malfunction
Approx. 0.0
  • Open in MAF meter power source circuit
  • Open or short in VG circuit
271.0 or more
  • Open in E2G circuit