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

### Circuit Description

The mass air flow (MAF) sensor measures the amount of air which passes through it into the engine during a given time. The PCM uses the mass air flow information to monitor engine operating conditions for fuel delivery calculations. A large quantity of air entering the engine indicates an acceleration or high load situation, while a small quantity of air indicates deceleration or idle. The MAF sensor produces a frequency signal which can be monitored using a scan tool. The frequency will vary within a range of around 2000 Hertz at idle to about 10,000 Hertz at maximum engine load. DTC P0103 will be set if the signal frequency from the MAF sensor is higher than the possible range of a normally operating MAF sensor.

### Conditions for Running the DTC

• | The engine is running.

• | TP angle is less than 50%.

• | System voltage is greater than 8 volts.

### Conditions for Setting the DTC

• | MAF signal frequency is greater than 11,500 Hertz.

• | The above conditions are present for longer than 0.5 seconds + 400 3X reference periods (133 crankshaft revolutions).

### Action Taken When the DTC Sets

• | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.

• | The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data.

### Conditions for Clearing the MIL/DTC

• | The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed.

• | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

• | The DTC can be cleared by using a scan tool.

### Diagnostic Aids

Check for the following conditions:

• | Poor connection at the PCM.

| Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.

• | Misrouted harness.

| Inspect the MAF sensor harness to ensure that it is not routed too close to high voltage wires such as spark plug leads.

• | Damaged harness.

| Inspect the wiring harness for damage. If the harness appears to be OK, observe the scan tool while moving connectors and wiring harnesses related to the MAF sensor. A change in the display will indicate the location of the malfunction.

If DTC P0103 cannot be duplicated, the information included in the Fail Records data can be useful in determining vehicle mileage since the DTC was last set.

### Test Description

The number(s) below refer to the Step number(s) on the Diagnostic Table:

1. This step verifies that the problem is present at idle.

2. A frequency reading with the MAF sensor connector disconnected indicates an Electromagnetic Interference (EMI) related malfunction or a poor connection.

3. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.

#### DTC P0103 - MAF Sensor Circuit High Frequency

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

1. Start the engine.
2. With the engine idling, monitor the MAF Frequency on the scan tool.

Is the MAF Frequency greater than the specified value?

11,500 Hz

Go to Step 4

Go to Step 3

3 |

1. Turn ON the ignition.
2. Review and record the scan tool Fail Records data.
3. Operate the vehicle within Fail Records conditions.
4. Monitor the Specific DTC info for DTC P0103, using a scan tool.

Does the scan tool indicate DTC P0103 failed this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4 |

1. Turn OFF the ignition.
2. Disconnect the MAF sensor connector.
3. Start the engine.
4. Monitor MAF Frequency on the scan tool.

Does the scan tool indicate MAF Frequency at the specified value?

0 Hz

Go to Step 5

Go to Step 7

5 |

1. Check for a poor connection at the MAF sensor harness terminals.
2. If a poor connection is found, replace loose terminal(s). Refer to Repairing Connector Terminals .

Was a problem found?

--

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. Check the MAF sensor harness for incorrect routing:

• | Near secondary ignition wires or coils.

• | Near other high voltage components (solenoids, relays, motors).

2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 10

Go to Step 8

8 |

1. Check MAF signal circuit terminal connections at the PCM.
2. If a poor connection is found, replace loose terminal(s). Refer to Repairing Connector Terminals .

Was a problem found?

--

Go to Step 10

Go to Step 9

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

1. Turn ON the ignition.
2. Review and record the scan tool Fail Records data.
3. Clear the DTCs.
4. Operate the vehicle within the Fail Records conditions.
5. Use a scan tool in order to monitor Specific DTC info for DTC P0103.

Does the scan tool indicate DTC P0103 failed this ignition?

--

Go to Step 2

System OK