P0100
3UZ-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 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.
MONITOR DESCRIPTION
If there is a defect in the 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.
This monitor runs for 3 seconds (the first 3 seconds of engine idle) after the engine is started (1 trip detection logic).
HINT: After confirming DTC P0100, P0102 or P0103, use the Techstream to confirm the MAF (to reach the MAF menu: Powertrain / Engine and ECT / Data List / MAF).
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. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, 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) Allow the engine to idle.
(c) Enter the following menus: Powertrain / Engine and ECT / Data List / MAF.
(d) Read the MAF value.
Result:
HINT: *: The value must change when the throttle valve is opened or closed.
C -- CHECK FOR INTERMITTENT PROBLEMS
B -- CHECK ECM (SENSOR GROUND)
A -- Continue to next step.
2. CHECK POWER SOURCE OF MASS AIR FLOW METER (+B VOLTAGE)
(a) Turn the ignition switch ON.
(b) Disconnect the M1 MAF meter connector.
(c) Measure the voltage of the wire harness side connector.
Standard voltage:
NG -- CHECK WIRE HARNESS (MASS AIR FLOW METER - EFI RELAY (Marking: EFI))
OK -- Continue to next step.
3. CHECK 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 WIRE HARNESS (MASS AIR FLOW METER - ECM)
(a) Disconnect the M1 MAF meter connector.
(b) Disconnect the E4 ECM connector.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:
NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- REPLACE MASS AIR FLOW METER
5. CHECK WIRE HARNESS (MASS AIR FLOW METER - EFI RELAY (Marking: EFI))
(a) Disconnect the M1 MAF meter connector.
(b) Remove the EFI relay from the engine room No. 1 relay block.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:
NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- CHECK ECM POWER SOURCE CIRCUIT
6. CHECK ECM (SENSOR GROUND)
(a) Measure the resistance of the ECM connector.
Standard resistance:
NG -- REPLACE ECM
OK -- Continue to next step.
7. CHECK WIRE HARNESS (MASS AIR FLOW METER - ECM)
(a) Disconnect the M1 MAF meter connector.
(b) Disconnect the E4 ECM connector.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:
NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- REPLACE MASS AIR FLOW METER