GSIC - Global Service Information Center

### DTC P0100/31 Mass or Volume Air Flow Circuit

### DTC P0102/31 Mass or Volume Air Flow Circuit Low Input

### DTC P0103/31 Mass or Volume Air Flow Circuit High Input

## for Preparation Click here

## 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.

DTC No. | DTC Detection Condition | Trouble Area

P0100/31

When MAF meter circuit has open or short for more than 3 seconds under 2,000 rpm engine speed
(1 trip detection logic)

1. Open or short in MAF meter circuit
2. MAF meter
3. ECM

P0102/31

When MAF meter circuit has open for more than 3 seconds under 2,000 rpm engine speed
(1 trip detection logic)

1. Open or short in MAF meter circuit
2. MAF meter
3. ECM

P0103/31

When MAF meter circuit has short for more than 3 seconds under 2,000 rpm engine speed
(1 trip detection logic)

1. Open or short in MAF meter circuit
2. MAF meter
3. ECM

HINT:

  When DTC P0100/31, P0102/31 or P0103/31 is detected, check the air-flow ratio by entering the following menus on the intelligent tester: Powertrain / Engine / Data List / MAF.

Air Flow Rate (gm/s) | Malfunction

Approximately 0.0

1. Open in MAF meter power source circuit
2. Open or short in VG circuit

174.0 or more | Open in EVG circuit

## WIRING DIAGRAM

## INSPECTION PROCEDURE

HINT:

  Read freeze frame data using the intelligent tester. 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, and other data from the time the malfunction occurred.

NOTICE:

  If the ECM is replaced, the new ECM needs initialization (Click here).

## When using intelligent tester:

1.READ DATA LIST (MASS AIR FLOW RATE)

1. Connect the intelligent tester to the DLC3.

1. Start the engine and turn the intelligent tester ON.

1. Enter the following menus: Powertrain / Engine / Data List / MAF.

1. Read the values.

   Result:

     Air Flow Rate (gm/s) | Proceed to
     0.0 | A
     174.0 or more | B
     Between 1 and 173.0* | C

   HINT:
     *: The value must changed when the throttle valve is opened or closed.

| B |

Go to step 6

| C |

CHECK FOR INTERMITTENT PROBLEMS

A |

2.CHECK MASS AIR FLOW METER (POWER SOURCE)

1. Disconnect the A4 MAF meter connector.

1. Turn the ignition switch ON.

1. Measure the voltage of the wire harness side connector.

   Standard voltage:

     Tester Connection | Specified Condition
     A4-1 - Body ground | 9 to 14 V

| NG |

Go to step 5

OK |

3.CHECK ECM (VG VOLTAGE)

1. Start the engine.

1. Measure the voltage of the ECM connector.

   Standard voltage:

     Tester Connection | Condition | Specified Condition
     E7-24 (VG) - E7-32 (EVG) | Engine idling | 0.5 to 3.4 V

   HINT:
     The A/C switch should be turned OFF.

| OK |

REPLACE ECM

NG |

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

1. Disconnect the A4 MAF meter connector.

1. Disconnect the E7 ECM connector.

1. Measure the resistance of the wire harness side connectors.

   Standard resistance:

     Tester Connection | Specified Condition
     A4-3 - E7-24 (VG) | Below 1 Ω
     A4-2 - E7-32 (EVG) | Below 1 Ω
     A4-3 or E7-24 (VG) - Body ground | 10 kΩ or higher
     A4-2 or E7-32 (EVG) - Body ground | 10 kΩ or higher

| NG |

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK |

REPLACE MASS AIR FLOW METER

5.CHECK WIRE HARNESS (MASS AIR FLOW METER - MAIN RELAY)

1. Disconnect the A4 MAF meter connector.

1. Remove the integration relay from the engine room J/B (Click here).

1. Disconnect the 1J integration relay connector.

1. Measure the resistance of the wire harness side connectors.

   Standard resistance:

     Tester Connection | Specified Condition
     A4-1 - 1J-5 | Below 1 Ω
     A4-1 or 1J-5 - Body ground | 10 kΩ or higher

| NG |

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK |

INSPECT ECM POWER SOURCE CIRCUIT

6.CHECK ECM (SENSOR GROUND)

1. Measure the resistance of the ECM connector.

   Standard resistance:

     Tester Connection | Specified Condition
     E7-32 (EVG) - Body ground | Below 1 Ω

| NG |

REPLACE ECM

OK |

7.CHECK WIRE HARNESS (MASS AIR FLOW METER- ECM)

1. Disconnect the A4 MAF meter connector.

1. Disconnect the E7 ECM connector.

1. Measure the resistance of the wire harness side connectors.

   Standard resistance:

     Tester Connection | Specified Condition
     A4-3 - E7-24 (VG) | Below 1 Ω
     A4-2 - E7-32 (EVG) | Below 1 Ω
     A4-3 or E7-24 (VG) - Body ground | 10 kΩ or higher
     A4-2 or E7-32 (EVG) - Body ground | 10 kΩ or higher

| NG |

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK |

REPLACE MASS AIR FLOW METER

## When not using intelligent tester:

1.CHECK ECM (VG VOLTAGE)

1. Start the engine.

1. Measure the voltage of the ECM connector.

   Standard voltage:

     Tester Connection | Condition | Specified Condition
     E7-24 (VG) - E7-32 (EVG) | Engine idling | 0.5 to 3.4 V

   HINT:
     The A/C switch should be turned OFF.

| OK |

REPLACE ECM

NG |

2.CHECK MASS AIR FLOW METER (POWER SOURCE)

1. Disconnect the A4 MAF meter connector.

1. Turn the ignition switch ON.

1. Measure the voltage of the wire harness side connector.

   Standard voltage:

     Tester Connection | Specified Condition
     A4-1 - Body ground | 9 to 14 V

| NG |

Go to step 4

OK |

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

1. Disconnect the A4 MAF meter connector.

1. Disconnect the E7 ECM connector.

1. Measure the resistance of the wire harness side connectors.

   Standard resistance:

     Tester Connection | Specified Condition
     A4-3 - E7-24 (VG) | Below 1 Ω
     A4-2 - E7-32 (EVG) | Below 1 Ω
     A4-3 or E7-24 (VG) - Body ground | 10 kΩ or higher
     A4-2 or E7-32 (EVG) - Body ground | 10 kΩ or higher

| NG |

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK |

REPLACE MASS AIR FLOW METER

4.CHECK WIRE HARNESS (MASS AIR FLOW METER - MAIN RELAY)

1. Disconnect the A4 MAF meter connector.

1. Remove the integration relay from the engine room J/B (Click here).

1. Disconnect the 1J integration relay connector.

1. Measure the resistance of the wire harness side connectors.

   Standard resistance:

     Tester Connection | Specified Condition
     A4-1 - 1J-5 | Below 1 Ω
     A4-1 or 1J-5 - Body ground | 10 kΩ or higher

| NG |

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK |

INSPECT ECM POWER SOURCE CIRCUIT