P0103
2UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0100: Mass Air Flow Circuit Malfunction
DTC P0100 - Mass Air Flow Circuit Malfunction
DTC P0102 - Mass Air Flow Circuit Low
DTC P0103 - Mass Air Flow Circuit High
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, 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 passing 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.
HINT: After confirming DTC P0100, P0102 or P0103, use the Techstream to confirm the MAF ratio from the All Data (to reach the All Data: Powertrain / Engine and ECT / Data List / All Data).
MONITOR DESCRIPTION
If there is a defect in the Mass Air Flow (MAF) meter or an open or short circuit, the voltage level will deviate outside the normal operating range. The ECM interprets this deviation as a defect in the MAF meter and sets a DTC.
Example: When the sensor output voltage is less than 0.2 V or more than 4.9 V and if either condition continues for more than 3 seconds, the ECM will set a DTC.
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 be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air/fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.
PROCEDURE
1. READ VALUE USING TECHSTREAM (MASS AIR FLOW RATE)
(a) Connect the Techstream to the DLC3.
(b) Allow the engine to idle.
(c) Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / MAF.
(d) Read the values displayed on the tester.
Result:
HINT: *1: The value must change when the throttle valve is open or closed.
C -- CHECK FOR INTERMITTENT PROBLEMS
B -- INSPECT ECM (SENSOR GROUND)
A -- Continue to next step.
2. INSPECT MASS AIR FLOW METER (POWER SOURCE VOLTAGE)
(a) Disconnect the M1 Mass Air Flow (MAF) meter connector.
(b) Turn the ignition switch ON.
(c) Measure the voltage of the wire harness side connector.
Standard voltage:
(d) Reconnect the MAF meter connector.
NG -- CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - EFI RELAY)
OK -- Continue to next step.
3. INSPECT ECM (VG VOLTAGE)
(a) Start the engine.
(b) Measure the voltage of the E4 ECM connector.
HINT: Move the shift lever to P or N and turn the A/C switch OFF.
Standard voltage:
OK -- REPLACE ECM
NG -- Continue to next step.
4. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)
(a) Disconnect the M1 mass air flow meter connector.
(b) Disconnect the E4 ECM connector.
(c) Measure the resistance between the wire harness side connectors.
Standard resistance:
(d) Reconnect the ECM connector.
(e) Reconnect the MAF connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE MASS AIR FLOW METER
5. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - EFI RELAY)
(a) Remove the EFI No. 2 fuse from the engine room R/B.
(b) Measure the resistance in the EFI No. 2 fuse.
Standard resistance:
Below 1 Ohms
(c) Reinstall the EFI No. 2 fuse.
(d) Disconnect the M1 mass air flow meter connector.
(e) Remove the EFI relay from the engine room R/B.
(f) Measure the resistance between the wire harness side connectors.
Standard resistance:
(g) Reconnect the MAF meter connector.
(h) Reinstall the EFI relay.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- CHECK ECM POWER SOURCE CIRCUIT
6. INSPECT ECM (SENSOR GROUND)
(a) Measure the resistance of the ECM connector.
Standard resistance:
NG -- REPLACE ECM
OK -- Continue to next step.
7. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)
(a) Disconnect the M1 mass air flow meter connector.
(b) Disconnect the E4 ECM connector.
(c) Measure the resistance between the wire harness side connectors.
Standard resistance:
(d) Reconnect the MAF meter connector.
(e) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE MASS AIR FLOW METER