P0102
2UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0102: Mass or Volume Air Flow Circuit Low Input
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 cold film element 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 entering the following menus: Powertrain / Engine and ECT / Data List / All Data / 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 higher 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
P0102:
P0103:
COMPONENT OPERATING RANGE
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT: Read freeze frame data using the Techstream. Freeze frame data records the engine condition when malfunctions are detected. 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 Techstream ON.
(d) Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / MAF.
(e) Read the values displayed on the Techstream.
Result
HINT: *: 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 (MASS AIR FLOW METER - ECM)
A -- Continue to next step.
2. INSPECT MASS AIR FLOW METER (POWER SOURCE VOLTAGE)
(a) Disconnect the D7 MAF meter connector.
(b) Turn the ignition switch to ON.
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:
NG -- CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - INTEGRATION RELAY)
OK -- Continue to next step.
3. INSPECT MASS AIR FLOW METER
(a) Inspect the mass air flow meter Inspection.
NG -- REPLACE MASS AIR FLOW METER
OK -- Continue to next step.
4. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)
(a) Disconnect the D7 MAF meter connector.
(b) Disconnect the D74 ECM connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM
5. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - INTEGRATION RELAY)
(a) Check the EFI NO. 2 fuse.
(1) Remove the EFI NO. 2 fuse from engine room relay block.
(2) Measure the resistance according to the value(s) in the table below
Standard resistance:
(3) Reinstall the EFI NO. 2 fuse.
(b) Disconnect the D7 MAF meter connector.
(c) Remove the integration relay from the engine room relay block.
(d) Measure the resistance according to the value(s) in the table below.
Standard resistance:
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- CHECK ECM POWER SOURCE CIRCUIT
6. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)
(a) Disconnect the D7 MAF meter connector.
(b) Disconnect the D74 ECM connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
7. CHECK HARNESS AND CONNECTOR (SENSOR GROUND)
(a) Disconnect the D7 MAF meter connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:
NG -- REPLACE ECM
OK -- REPLACE MASS AIR FLOW METER