P0102

3UR-FE ENGINE CONTROL: SFI SYSTEM: P0102, P0103: Mass or Volume Air Flow Circuit Low 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 the wire and internal thermistor. 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 stored, the ECM enters fail-safe mode. During fail-safe mode, the ignition timing is calculated by the ECM, according to the engine speed and throttle valve position. Fail-safe mode continues until a pass condition is detected.









HINT
When any of these DTCs is output, 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 stores DTC(s).

Example:

When the sensor output voltage remains at below 0.2 V, or higher than 4.9 V for more than 3 seconds, the ECM stores DTC(s).

If the malfunction is not repaired successfully, a DTC is stored 3 seconds after the engine is next started.

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS





TYPICAL MALFUNCTION THRESHOLDS

P0102:





P0103:





COMPONENT OPERATING RANGE





CONFIRMATION DRIVING PATTERN





1. Connect the Techstream to the DLC3.

2. Turn the engine switch on (IG) and turn the Techstream on.

3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC operation).

4. Turn the engine switch off and wait for at least 30 seconds.

5. Turn the engine switch on (IG) and turn the Techstream on [A].

6. Start the engine.

7. Idle the engine for 5 seconds [B].

8. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [C].

9. Read the DTCs.

HINT
- If a DTC is output, the system is malfunctioning.
- If a DTC is not output, perform the following procedure.

10. Run the engine at an engine speed of 4000 rpm or more for 5 seconds [D].

11. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [E].

12. Read the pending DTCs.

HINT
- If a pending DTC is output, the system is malfunctioning.
- If a pending DTC is not output, perform the following procedure.

13. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

14. Input the DTC: P0102 or P0103.

15. Check the DTC judgment result.





HINT
- If the judgment result shows NORMAL, the system is normal.
- If the judgment result shows ABNORMAL, the system has a malfunction.
- If the judgment result shows INCOMPLETE or UNKNOWN, perform steps [B] and [C] again.

16. If no pending DTC is output, perform a universal trip and check for permanent DTCs Reading and Clearing Diagnostic Trouble Codes.

HINT
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.

WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
Inspect the fuses for circuits related to this system before performing the following 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 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 C3 Mass Air Flow (MAF) meter connector.

(b) Turn the engine switch on (IG).

(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) Disconnect the MAF meter connector.





(b) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG).

(d) Turn the Techstream on.

(e) Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / MAF.

(f) Check the MAF value when air is blown to the mass air flow meter, as shown in the illustration.

OK:

The MAF value changes.

NG -- REPLACE MASS AIR FLOW METER Removal
OK -- Continue to next step.

4. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)





(a) Disconnect the C3 MAF meter connector.

(b) Disconnect the C53 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 Removal

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 the 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 C3 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 ECM Power Source Circuit

6. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)





(a) Disconnect the C3 MAF meter connector.

(b) Disconnect the C53 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 C3 MAF meter connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:





NG -- REPLACE ECM Removal

OK -- REPLACE MASS AIR FLOW METER Removal