P0103

3UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0100,P0102,P0103: Mass Air Flow Circuit Malfunction

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 P0102 or P0103, use the Techstream to confirm the MAF (to reach the MAF menu: Powertrain / Engine / Data List / MAF).

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

P0102:

P0103:

COMPONENT OPERATING RANGE

CONFIRMATION DRIVING PATTERN

- Connect the Techstream to the DLC3.

- Turn the ignition switch to ON and turn the Techstream on.

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

- Turn the ignition switch off and wait for at least 30 seconds.

- Turn the ignition switch to ON and turn the Techstream on [A].

- Start the engine.

- Idle the engine for 5 seconds [B].

- Enter the following menus: Powertrain / Engine / Trouble Codes [C].

- Read the DTCs.

HINT
- If a DTC is output, the system is malfunctioning.
- If a DTC is not output, perform the following procedure.
- Enter the following menus: Powertrain / Engine / Utility / All Readiness.

- Input the DTC: P0102 or P0103.

- Check the DTC judgment result.

HINT
If the judgment result shows INCOMPLETE or UNKNOWN, perform steps [B] through [C] again.

- If no 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

INSEPCTION 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 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. CHECK DTC OUTPUT

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Clear DTCs Reading and Clearing Diagnostic Trouble Codes.

(e) Allow the engine to idle for 1 minute or more.

(f) Enter the following menus: Powertrain / Engine / Trouble Codes.

(g) Read the DTCs.

Result

B -- CHECK FOR INTERMITTENT PROBLEMS
A -- Continue to next step.

2. READ VALUE USING TECHSTREAM (MAF)

(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 to the air cleaner case (installed to the vehicle).
- During the test, do not use an exhaust air duct on the exhaust tail pipe assembly.
(b) Connect the Techstream to the DLC3.

(c) Turn the ignition switch to ON (do not start the engine).

(d) Turn the Techstream on.

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

(f) Wait 30 seconds, and read the values on the Techstream.

Result

B -- CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - GROUND)
A -- Continue to next step.

3. INSPECT MASS AIR FLOW METER (POWER SOURCE VOLTAGE)

(a) Disconnect the mass air flow 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 - EFI RELAY)
OK -- Continue to next step.

4. INSPECT MASS AIR FLOW METER

(a) Remove the mass air flow meter with the wire harness connector connected.

(b) Connect the Techstream to the DLC3.

(c) Turn the ignition switch to ON.

(d) Turn the Techstream on.

(e) Enter the following menus: Powertrain / Engine / Data List / 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 Service and Repair
OK -- Continue to next step.

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

(a) Disconnect the mass air flow meter connector.

(b) Disconnect the ECM connector.

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

Standard Resistance (Check for Open):

Standard Resistance (Check for Short):

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE ECM Service and Repair

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

(a) Disconnect the mass air flow meter connector.

(b) Remove the EFI relay from the engine room No. 2 relay block.

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

Standard Resistance (Check for Open):

Standard Resistance (Check for Short):

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- CHECK ECM POWER SOURCE CIRCUIT ECM Power Source Circuit

7. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - GROUND)

(a) Disconnect the mass air flow meter connector.

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

Standard Resistance:

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

OK -- REPLACE MASS AIR FLOW METER Service and Repair

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

Standard Resistance (Check for Short):

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE ECM Service and Repair