Toyota 2GR-FE Manual page 298

ES–142
MONITOR DESCRIPTION
The MAF meter is a sensor that measures the amount of air flowing through the throttle valve. The ECM
uses this information to determine the fuel injection time and to provide an appropriate air-fuel ratio.
Inside the MAF meter, 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 ECM heats it to a specific temperature. The flow of
incoming air cools both the wire and an internal thermistor, affecting their resistance. To maintain a
constant current value, the ECM varies the voltage applied to these components of the MAF meter. The
voltage level is proportional to the airflow through the sensor, and the ECM uses it to calculate the intake
air volume. If there is a defect in the sensor, or an open or short in the circuit, the voltage level deviates
from the normal operating range. The ECM interprets this deviation as a malfunction in the MAF meter
and sets the DTC.
Example:
If the voltage is more than 2.2 V, or less than 1.48 V while idling, the ECM determines that there is a
malfunction in the MAF meter and sets the DTC.
ES
MONITOR STRATEGY
Related DTCs
Required Sensors/Components (Main)
Required Sensors/Components (Sub)
Frequency of Operation
Duration
MIL Operation
Sequence of Operation
TYPICAL ENABLING CONDITIONS
Monitor runs whenever following DTCs are not present
TP (Throttle position) sensor voltage
Engine
Battery voltage
ECT
IAT sensor circuit
ECT sensor circuit
CKP sensor circuit
TP sensor circuit
FTP sensor circuit
EVAP leak detection pump
EVAP vent valve
TYPICAL MALFUNCTION THRESHOLDS
Average engine load
WIRING DIAGRAM
Refer to DTC P0100 (See page ES-127).
2GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
P0101: Mass air flow meter rationality
Mass air flow meter
Crankshaft position sensor, engine coolant temperature sensor and
throttle position sensor
Continuos
10 seconds
2 driving cycles
None
P0115 - P0118 (ECT sensor)
P0120 - P0223, P2135 (TP sensor)
P0125 (Insufficient ECT for closed loop)
P0335 (CKP sensor)
P0340, P0341 (CMP sensor)
0.24 V or more
Running
10.5 V or more
70°C (158°F) or more
OK
OK
OK
OK
OK
OK
OK
Less than 0.838 %, or more than 1.287 %