P0100
2AZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0100,P0102,P0103: Mass or Volume Air Flow Circuit
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 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 the 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 given 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 in 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.
The circuit is constructed so that the platinum hot wire and the temperature sensor create a bridge circuit, and the power transistor is controlled so that the potentials of A and B remain equal to maintain the predetermined temperature.
HINT: When any of these DTCs are set, the ECM enters fail-safe mode. During fail-safe mode, the ignition timing is calculated by the ECM, according to the engine RPM and throttle valve position. Fail-safe mode continues until a pass condition is detected.
HINT: When any of these DTCs are set, check the air-flow rate by selecting the following menu items on the Techstream: Powertrain / Engine and ECT / Data List / MAF.
MONITOR DESCRIPTION
If there is a defect in the MAF meter or an open or short circuit, the voltage level deviates from the normal operating range. The ECM interprets this deviation as a malfunction in the MAF meter and sets a DTC.
Example:
When the sensor output voltage remains less than 0.2 V, or more than 4.9 V, for more than 3 seconds, the ECM sets a DTC.
If the malfunction is not repaired successfully, a DTC is set 3 seconds after the engine is next started.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
TYPICAL MALFUNCTION THRESHOLDS
P0100:
P0102:
P0103:
COMPONENT OPERATING RANGE
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT: Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.
PROCEDURE
1. READ VALUE USING TECHSTREAM (MASS AIR FLOW RATE)
(a) Connect the Techstream to the DLC3.
(b) Start the engine.
(c) Turn the tester on.
(d) Select the following menu items: Powertrain / Engine and ECT / Data List / MAF.
(e) Read the values displayed on the tester.
Result:
HINT: *1: The value must change when the throttle valve is open or closed with the engine running.
C -- CHECK FOR INTERMITTENT PROBLEMS
B -- CHECK HARNESS AND CONNECTOR (SENSOR GROUND)
A -- Continue to next step.
2. INSPECT MASS AIR FLOW METER (POWER SOURCE VOLTAGE)
(a) Disconnect the C2 Mass Air Flow (MAF) meter connector.
(b) Turn the ignition switch to the ON position.
(c) Measure the voltage between the terminal of the wire harness side connector and body ground.
Standard voltage:
(d) Reconnect the MAF meter connector.
NG -- CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ENGINE ROOM J/B)
OK -- Continue to next step.
3. INSPECT MASS AIR FLOW METER
(a) Read the values using the Techstream (MAF).
NOTICE:
- Turn the ignition switch off.
- Perform the inspection with the vehicle indoors and on a level surface.
- Perform the inspection of the mass air flow meter while it is installed in the air cleaner case (installed on the vehicle).
- During the test, make sure that an exhaust air duct is not drawing air through the exhaust pipe.
(1) Connect the Techstream to the DLC3.
(2) Turn the ignition switch to ON (do not start the engine).
(3) Turn the Techstream on.
(4) Select the following menu items: Powertrain / Engine and ECT / Data List / MAF.
(5) Wait for 30 seconds, and read the values on the Techstream.
Standard value:
Less than 0.50 gm/sec
(b) Inspect the mass air flow meter.
(1) Remove the mass air flow meter.
(2) Using a work light, check that the platinum filament (heater portion) in the mass air flow meter has no foreign matter attached.
OK:
No foreign matter attached.
(3) Reinstall the mass air flow meter.
NG -- REPLACE MASS AIR FLOW METER
OK -- Continue to next step.
4. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)
(a) Disconnect the C2 MAF meter connector.
(b) Disconnect the C24 ECM connector.
(c) Measure the resistance between the terminals of the wire harness side connectors.
Standard resistance (Check for open):
Standard resistance (Check for short):
(d) Reconnect the MAF meter connector.
(e) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM
5. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ENGINE ROOM J/B)
(a) Inspect the EFI No. 3 fuse.
(1) Remove the EFI No. 3 fuse from the engine room R/B.
(2) Measure the EFI No. 3 fuse resistance.
Standard resistance:
Below 1 Ohms
(3) Reinstall the EFI No. 3 fuse.
(b) Disconnect the C2 MAF meter connector.
(c) Remove the engine room J/B from the engine room R/B.
(d) Disconnect the 1E engine room J/B connector.
(e) Measure the resistance between the terminals.
Standard resistance (Check for open):
Standard resistance (Check for short):
(f) Reconnect the MAF meter connector.
(g) Reconnect the engine room J/B connector.
(h) Reinstall the engine room J/B.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- CHECK ECM POWER SOURCE CIRCUIT
6. CHECK HARNESS AND CONNECTOR (SENSOR GROUND)
(a) Disconnect the C2 MAF meter connector.
(b) Measure the resistance.
Standard resistance:
(c) Reconnect the MAF meter connector.
OK -- REPLACE MASS AIR FLOW METER
NG -- Continue to next step.
7. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)
(a) Disconnect the C2 MAF meter connector.
(b) Disconnect the C24 ECM connector.
(c) Measure the resistance between the terminals of the wire harness side connectors.
Standard resistance (Check for open):
Standard resistance (Check for short):
(d) Reconnect the MAF meter connector.
(e) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM