1Nz-Fe Engine Control. Dtc P0102 Mass Or Volume Air Flow Circuit Low Input

The mass air flow 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 mass air flow 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 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 any of these DTCs is 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.

Yaris. Ncp93, 131.1Nz-Fe Engine Control.Sfi System (For Sedan).
Dtc
P0102 Mass Or Volume Air Flow Circuit Low Input

DTC No.	DTC Detection Condition	Trouble Area
P0102	The mass air flow meter voltage is less than 0.2 V for 3 seconds. (1 trip detection logic: Engine speed is less than 4000 rpm) (2 trip detection logic: Engine speed is 4000 rpm or more)	Open or short in mass air flow meter circuit Mass air flow meter ECM
P0103	The mass air flow meter voltage is more than 4.9 V for 3 seconds. (1 trip detection logic: Engine speed is less than 4000 rpm) (2 trip detection logic: Engine speed is 4000 rpm or more)	Open or short in mass air flow meter circuit Mass air flow meter ECM

HINT:

When any of these DTCs are output, check the air-flow rate using the Techstream. Enter 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 power source circuit Open or short in VG circuit
160.0 or more	Open in E2G circuit

MONITOR DESCRIPTION

If there is a defect in the mass air flow 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 mass air flow meter circuit and stores a DTC.
Example:
When the sensor output voltage remains below 0.2 V or higher than 4.9 V for more than 3 seconds, the ECM stores a DTC.
If the malfunction is not repaired successfully, a DTC is stored 3 seconds after the engine is next started.

MONITOR STRATEGY

Related DTCs	P0102: Mass Air Flow Meter Range Check (Low Voltage) P0103: Mass Air Flow Meter Range Check (High Voltage)
Required Sensors/Components (Main)	Mass air flow meter
Required Sensors/Components (Related)	Crankshaft position sensor
Frequency of Operation	Continuous
Duration	3 seconds
MIL Operation	Immediate: Engine speed less than 4000 rpm 2 driving cycles: Engine speed 4000 rpm or more
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever following DTCs not present

None

TYPICAL MALFUNCTION THRESHOLDS

P0102:
Mass air flow meter voltage	Less than 0.2 V

P0103:
Mass air flow meter voltage	More than 4.9 V

COMPONENT OPERATING RANGE

Mass air flow meter voltage

0.2 V or more, and 4.9 V or less

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 procedure).
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 and ECT / Trouble Codes [C].
Read pending DTCs.
HINT:
1. If a pending DTC is output, the system is malfunctioning.
2. If a pending DTC is not output, perform the following procedure.
Run the engine at an engine speed of 4000 rpm or more for 5 seconds [D].
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [E].
Read pending DTCs.
HINT:
1. If a pending DTC is output, the system is malfunctioning.
2. If a pending DTC is not output, perform the following procedure.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P0102 or P0103.

Check the DTC judgment result.

Techstream Display	Description
NORMAL	DTC judgment completed System normal
ABNORMAL	DTC judgment completed System abnormal
INCOMPLETE	DTC judgment not completed Perform driving pattern after confirming DTC enabling conditions
N/A	Unable to perform DTC judgment Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

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 N/A, perform steps [B] through [E] again.

If the no pending DTC is output, perform a universal trip and check for permanent DTCs (YARIS_NCP93 RM000000PDK0T5X.html).
HINT:
1. If a permanent DTC is output, the system is malfunctioning.
2. 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. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. 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.

1.READ DTC OUTPUT

Connect the Techstream to the DLC3.

Turn the ignition switch to ON.

Turn the Techstream on.

Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

Read DTCs.
Result
Result
Proceed to
DTC P0102 is output
A
DTC P0103 is output
B

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

Go to step 5

A

2.CHECK TERMINAL VOLTAGE (POWER SOURCE OF MASS AIR FLOW METER)

Disconnect the mass air flow meter connector.

Turn the ignition switch to ON.

Measure the voltage according to the value(s) in the table below.
Standard Voltage:
Tester Connection
Switch Condition
Specified Condition
C63-1 (+B) - Body ground
Ignition switch ON
11 to 14 V
Text in Illustration
*a
Front view of wire harness connector
(to Mass Air Flow Meter)

Text in Illustration
*a	Front view of wire harness connector (to Mass Air Flow Meter)

Go to step 7

OK

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

Disconnect the mass air flow meter connector.

Disconnect the ECM connector.

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

Standard Resistance:

Tester Connection
Condition
Specified Condition
C63-3 (VG) - C51-91 (VG)
Always
Below 1 Ω
C63-2 (E2G) - C51-92 (E2G)
Always
Below 1 Ω
C63-3 (VG) or C51-91 (VG) - Body ground
Always
10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.INSPECT MASS AIR FLOW METER

Inspect the mass air flow meter, referring to the On-vehicle Inspection for Mass Air Flow Meter (YARIS_NCP93 RM000003VI100FX.html).

Inspect the mass air flow meter, referring to the Inspection for Mass Air Flow Meter (YARIS_NCP93 RM000003VJA00FX.html).

Inspect the function of the mass air flow meter.
1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine and ECT / Data List / MAF.
5. Start the engine.
6. Check that the MAF value changes when the engine is raced.
  OK:
  The reading changes.
  HINT:
  Perform "Inspection After Repair" after replacing the mass air flow meter (YARIS_NCP93 RM000004NJD006X.html).

REPLACE MASS AIR FLOW METER (YARIS_NCP93 RM000003VI000HX.html)

REPLACE ECM (YARIS_NCP93 RM000001CN002IX.html)

5.CHECK HARNESS AND CONNECTOR (SENSOR GROUND)

Disconnect the mass air flow meter connector.

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

Standard Resistance:

Tester Connection
Condition
Specified Condition
C63-2 (E2G) - Body ground
Always
Below 1 Ω
HINT:
Perform "Inspection After Repair" after replacing the mass air flow meter (YARIS_NCP93 RM000004NJD006X.html).

Go to step 6

REPLACE MASS AIR FLOW METER (YARIS_NCP93 RM000003VI000HX.html)

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

Disconnect the mass air flow meter connector.

Disconnect the ECM connector.

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

Standard Resistance:

Tester Connection
Condition
Specified Condition
C63-2 (E2G) - C51-92 (E2G)
Always
Below 1 Ω

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE ECM (YARIS_NCP93 RM000001CN002IX.html)

7.CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - NO. 1 INTEGRATION RELAY)

Disconnect the mass air flow meter connector.

Remove the No. 1 integration relay from the engine room relay block.

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

Standard Resistance:

Tester Connection
Condition
Specified Condition
C63-1 (+B) - 1E-3
Always
Below 1 Ω
C63-1 (+B) or 1E-3 - Body ground
Always
10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

CHECK ECM POWER SOURCE CIRCUIT (YARIS_NCP93 RM000001F7102NX.html)

Tester Connection	Switch Condition	Specified Condition
C63-1 (+B) - Body ground	Ignition switch ON	11 to 14 V

Tester Connection	Condition	Specified Condition
C63-3 (VG) - C51-91 (VG)	Always	Below 1 Ω
C63-2 (E2G) - C51-92 (E2G)	Always	Below 1 Ω
C63-3 (VG) or C51-91 (VG) - Body ground	Always	10 kΩ or higher