For 1990-2009 cars
Engine Controls Components
Information Sensors
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The Mass Air Flow (MAF) sensor measures the amount of air ingested by the engine. The direct measurement of the air entering the engine is more accurate than calculating the airflow from the MAP, the IAT, and the engine speed (speed/density). The MAF sensor has a battery feed, a ground, and a signal circuit.

The MAF sensor used on this engine is a hot wire type. This engine uses the MAF sensor in order to measure air flow rate. The MAF output frequency is a function of the power required to keep the air flow sensing elements (hot wires) at a fixed temperature above the ambient temperature. Air flowing through the sensor cools the sensing elements. The amount of cooling is proportional to the amount of air flow. The MAF sensor requires a greater amount of current in order to maintain the hot wires at a constant temperature as the air flow increases. The MAF sensor converts the changes in current draw to a frequency signal read by the PCM. The PCM calculates the air flow (grams per second) based on this signal.

The PCM monitors the MAF sensor frequency. The PCM determines if the sensor is stuck low, stuck high, not providing the airflow value expected for a given operating condition, or that the signal appears to be stuck based on a lack of signal variation expected during the normal operation. This diagnostic tests for too high an airflow rate. This DTC sets when the PCM detects that the MAF sensor frequency is above a predetermined value.

### Conditions for Running the DTC

• | The engine speed is greater than 300 RPM.

• | The system voltage is greater than 8.0 volts.

### Conditions for Setting the DTC

• | The MAF frequency is greater than 14,000 Hz.

• | All conditions met for less than 1 second.

### Action Taken When the DTC Sets

• | The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

• | The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure records.

• | The PCM utilizes speed density (RPM, MAP, IAT) for fuel management.

### Conditions for Clearing the MIL/DTC

• | The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

• | A last test failed, or current DTC, clears when the diagnostic runs and does not fail.

• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

• | Use a scan tool in order to clear the MIL and the DTC.

### Diagnostic Aids

Important:

• | Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

• | For any test that requires probing the PCM or component harness connectors, use the Connector Test Adapter Kit J 35616 . Using this kit prevents damage to the harness connector terminals. Refer to Using Connector Test Adapters in Wiring Systems.

• | Water entering the air intake system that reaches the MAF sensor could cause this DTC to set. The water rapidly cools the hot wires in the sensor, causing a false indication of excessive airflow. Inspect the following areas for evidence (witness marks) of water intrusion:

- | AIR system

- | Intake air system

• | The following may cause an intermittent:

- | Mis-routed harness

- | Rubbed through wire insulation

- | Broken wire inside the insulation

- | A poor connection in the ignition feed circuit to the MAF sensor can cause a DTC P0103 to set.

• | For an intermittent, refer to Symptoms .

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. Monitoring the MAF sensor frequency determines if the fault is present or the malfunction is intermittent. A poor connection at the MAF sensor or at the fuse causes this DTC to set.

2. Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed.

3. This step tests for electro-magnetic interference on the MAF sensor signal circuit. There should be no signal indicated on the scan tool with the sensor disconnected.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Idle the engine.
2. Monitor the MAF sensor display on the Engine 2 Data List of the scan tool.

Is the MAF sensor frequency above the specified value?

14,000 Hz

Go to Step 4

Go to Step 3

3 |

1. Turn ON the ignition leaving the engine OFF.
2. Review the Freeze Frame and/or Failure Records data for this DTC and observe the parameters.
3. Turn OFF the ignition for 15 seconds.
4. Start the engine.
5. Operate the vehicle within the conditions required for this diagnostic to run, and as close to the conditions recorded in the Freeze Frame/Failure Records as possible. Special operating conditions that you need to meet before the PCM will run this diagnostic, where applicable, are listed in Conditions for Running the DTC.
6. Select the Diagnostic Trouble Code (DTC) option, the Specific DTC option, then enter the DTC number using the scan tool.

Does the scan tool indicate that this diagnostic failed this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4 |

1. Turn OFF the ignition.
2. Disconnect the MAF sensor connector.
3. Idle the engine.
4. Monitor the MAF sensor frequency using the scan tool.

Does scan tool indicate a MAF sensor frequency?

--

Go to Step 7

Go to Step 5

5 |

1. Inspect for a poor connection at the MAF sensor harness terminals. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
2. If you find a poor connection, repair the condition as necessary. Refer to Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 6

6 | Replace the MAF sensor. Refer to Mass Airflow Sensor Replacement . Is the action complete? | -- | Go to Step 10 | --
7 |

1. Inspect the MAF sensor harness for incorrect routing at the following locations:

• | Near secondary ignition wires or components.

• | Other high current components. Such as solenoids, relays, and motors.

2. Correct the harness routing if you find incorrect routing.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 8

8 |

1. Inspect the MAF sensor signal circuit terminal connections at the PCM connector C1 located on the opposite side of the manufacturer's logo. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
2. If you find a poor connection, repair the condition as necessary. Refer to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 9

9 | Important:: Program the replacement PCM. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete? | -- | Go to Step 10 | --
10 |

1. Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool.
2. Idle the engine at the normal operating temperature.
3. Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.

Does the scan tool indicate that this test ran and passed?

--

Go to Step 11

Go to Step 2

11 | Select the Capture Info option and the Review Info option using the scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table. | System OK