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DTC P0102 Mass or Volume Air Flow Circuit Low Input
DTC P0103 Mass or Volume Air Flow Circuit High Input

for Preparation Click here

DESCRIPTION

The mass air flow meter sub-assembly 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 mass air flow meter sub-assembly, 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 flow of incoming air cools both the wire and an internal thermistor, affecting their resistance. To maintain a constant temperature value of the hot wire, current is applied to these components in the mass air flow meter sub-assembly. 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 temperature sensor 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 either 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 speed and throttle valve position. Fail-safe mode continues until a pass condition is detected.

DTC No.	DTC Detection Condition	Trouble Area
P0102	Mass air flow meter voltage less than 0.2 V for 3 seconds (1 trip detection logic)	Open or short in mass air flow meter sub-assembly circuit Mass air flow meter sub-assembly ECM
P0103	Mass air flow meter voltage more than 4.9 V for 3 seconds (1 trip detection logic)	Open or short in mass air flow meter sub-assembly circuit Mass air flow meter sub-assembly ECM

HINT:

When any of these DTCs are set, check the air-flow rate by entering the following menus: Powertrain / Engine and ECT / Data List / MAF.

Mass Air Flow Rate (gm/sec)	Malfunction
Approximately 0.0	Open in mass air flow meter sub-assembly power source circuit Open or short in VG circuit
271.0 or more	Open in E2G circuit

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 intelligent tester. 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.

1.READ DTC OUTPUT

Connect the intelligent tester to the DLC3.

Turn the power switch on (IG).

Turn the tester on.

Enter the following menus: Powertrain / Engine and ECT / DTC.

Read the DTCs.

Result:

Result
Proceed to
DTC P0102 is output
A
DTC P0103 is output
B

Go to step 5

A

2.INSPECT MASS AIR FLOW METER SUB-ASSEMBLY (POWER SOURCE VOLTAGE)

Disconnect the mass air flow meter sub-assembly connector.

Turn the power switch on (IG).

Measure the voltage according to the value(s) in the table below.
Standard Voltage:
Tester Connection
Switch Condition
Specified Condition
D5-3 (+B) - Body ground
Power switch on (IG)
11 to 14 V
Text in Illustration
*1
Front view of wire harness connector
(to Mass Air Flow Meter Sub-assembly)

Text in Illustration
*1	Front view of wire harness connector (to Mass Air Flow Meter Sub-assembly)

Reconnect the mass air flow meter sub-assembly connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR (EFI MAIN RELAY - MASS AIR FLOW METER SUB-ASSEMBLY)

OK

3.CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - ECM)

Disconnect the mass air flow meter sub-assembly connector.

Disconnect the ECM connector.

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

Standard Resistance (Check for Open):

Tester Connection
Condition
Specified Condition
D5-5 (VG) - D28-94 (VG)
Always
Below 1 Ω
D5-4 (E2G) - D28-117 (E2G)

Standard Resistance (Check for Short):

Tester Connection
Condition
Specified Condition
D5-5 (VG) or D28-94 (VG) - Body ground
Always
10 kΩ or higher

Text in Illustration
*1
Front view of wire harness connector
(to Mass Air Flow Meter Sub-assembly)
*2
Front view of wire harness connector
(to ECM)

Text in Illustration
*1	Front view of wire harness connector (to Mass Air Flow Meter Sub-assembly)	*2	Front view of wire harness connector (to ECM)

Reconnect the mass air flow meter sub-assembly connector.

Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - ECM)

OK

4.INSPECT MASS AIR FLOW METER SUB-ASSEMBLY

Perform On-vehicle inspection (Click here).

Perform Inspection (Click here).

Inspect the function of the mass air flow meter sub-assembly.
1. Remove the mass air flow meter sub-assembly with the connector connected.
2. Connect the intelligent tester to the DLC3.
3. Turn the power switch on (IG).
4. Turn the tester on.
5. Enter the following menus: Powertrain / Engine and ECT / Data List / MAF.
6. Blow air to the mass air flow meter sub-assembly and check that the intake air amount reading changes.

OK:: The reading changes.

REPLACE MASS AIR FLOW METER SUB-ASSEMBLY (Click here)

REPLACE ECM (Click here)

5.CHECK HARNESS AND CONNECTOR (SENSOR GROUND)

Disconnect the mass air flow meter meter sub-assembly connector.

Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Connection
Condition
Specified Condition
D5-4 (E2G) - Body ground
Always
Below 1 Ω
Text in Illustration
*1
Front view of wire harness connector
(to Mass Air Flow Meter Sub-assembly)

Text in Illustration
*1	Front view of wire harness connector (to Mass Air Flow Meter Sub-assembly)

Reconnect the mass air flow meter sub-assembly connector.

Go to step 6