1A
DTC P0101: Mass Air Flow Circuit Range / Performance
Wiring Diagram
1. MAF and IAT sensor 3. Main relay 5. To other sensors
2. Ignition switch 4. ECM    
DTC Detecting Condition and Trouble Area
DTC detecting condition Trouble area
MAF volume is greater than 62 g/sec even if engine revolution is less than 900 rpm and intake manifold pressure is less than 70 kPa (10.15 psi) with TP less than 1.5°.
MAF volume is lower than 8 g/sec even if engine revolution is more than 2500 rpm and intake manifold pressure is more than 55 kPa (7.98 psi) with TP more than 15°.
(2 driving cycle detection logic)
Air intake system (clog or leakage)
MAF sensor circuit
MAF sensor
TP sensor
ECM
DTC Confirmation Procedure
WARNING:
When performing a road test, select a place where there is no traffic or possibility of a traffic accident and be very careful during testing to avoid occurrence of an accident.
Road test should be carried out with 2 person, a driver and a tester, on a level road.
NOTE:
Check to make sure that the following conditions are satisfied when using this “DTC Confirmation Procedure”.
Intake air temperature at engine start: –10 °C (14 °F) to 80 °C (176 °F)
Intake air temperature: –10 °C (14 °F) to 70 °C (158 °F)
Engine coolant temperature: 70 °C (158 °F) to 150 °C (302 °F)
Altitude (barometric pressure): 2400 m, 8000 ft or less (560 mmHg, 75 kPa or more)
1) With ignition switch turned OFF, connect scan tool.
2) Turn ON ignition switch and clear DTC using scan tool.
3) Start engine and warm up to normal operating temperature. (ECT approx. 90 – 95 °C, 194 – 203 °F)
4) Drive vehicle with engine speed: more than 2500 rpm for 1 min.
5) Increase vehicle speed to 80 km/h (45 mile/h) at 5th gear.
6) Release accelerator pedal to decrease vehicle speed till 40 km/h (25 mile/h).
7) Stop vehicle and run it idle for 1 min.
8) Check DTC and pending DTC.
DTC Troubleshooting
Step Action YES NO
1
Was “Engine and Emission Control System Check” performed?
Go to Step 2.
2
Visual inspection
Check MAF sensor and air intake system for:
1) Objects which block measuring duct and resistor of MAF sensor.
2) Other air flow which does not pass the MAF sensor.
Are there in good condition?
Go to Step 3.
Repair or replace.
3
MAF sensor and its circuit check
1) With ignition switch turned OFF, install scan tool.
2) Start engine and warm up to normal operation temperature.
3) Check MAF value using scan tool. (Refer to Scan Tool Data:M13A with VVT for normal value.)
Is each value within specified?
Go to Step 11.
Go to Step 4.
4
MAF sensor output voltage check
1) Turn OFF ignition switch.
2) Measure voltage between “E119-14” and “E119-32” terminals of ECM connector referring to Mass Air Flow (MAF) and Intake Air Temperature (IAT) Sensor On-Vehicle Inspection (With VVT):M13A .
Is each value within specified?
Poor “E119-14” and/or “E119-32” terminal connection. If OK, substitute a known-good ECM and recheck.
Go to Step 5.
5
MAF sensor power supply voltage check
1) Disconnect connector from MAF and IAT sensor with ignition switch turned OFF.
2) Turn ON ignition switch, measure voltage between engine ground and “BLU/BLK” wire terminal (2) of MAF and IAT sensor connector (1).
Is voltage 10 – 14 V?
Go to Step 6.
“BLU/BLK” wire in open circuit.
6
MAF sensor ground circuit check
1) Turn OFF ignition switch, measure resistance between “YEL/BLK” wire terminal of MAF and IAT sensor connector and engine ground.
Is resistance below 5 Ω?
Go to Step 8.
Go to Step 7.
7
Ground circuit check
1) Measure resistance between “E119-32” terminal of ECM connector and vehicle body ground.
Is resistance below 5 Ω?
“YEL/BLK” wire in open or high resistance circuit.
ECM grounds “E119-1”, “E117-2” and/or “E117-1” circuit in open or high resistance. If wires are OK, substitute a known-good ECM and recheck.
8
MAF sensor signal circuit check
1) Disconnect connectors from ECM with ignition switch turned OFF.
2) Turn ON ignition switch, measure voltage between “YEL/GRN” wire terminal of MAF and IAT sensor connector and engine ground.
Is voltage 0 V?
Go to Step 9.
“YEL/GRN” wire shorted to others circuit.
9
MAF sensor signal circuit check
1) Turn OFF ignition switch, measure resistance between “YEL/GRN” wire terminal of MAF and IAT sensor connector and vehicle body ground.
Is resistance infinity?
Go to Step 10.
“YEL/GRN” wire shorted to ground circuit.
10
MAF sensor signal circuit check
1) Measure resistance between “YEL/GRN” wire terminal of MAF and IAT sensor connector and “E119-14” terminal of ECM connector.
Is resistance below 3 Ω?
Faulty MAF and IAT sensor.
“YEL/GRN” wire in open or high resistance circuit.
11
Is DTC P0121 detected?
Substitute a known-good ECM and recheck.
NOTE:
Upon completion of inspection and repair work, perform “DTC Confirmation Procedure” and confirm that the trouble has been corrected.