For 1990-2009 cars
Engine Controls Components
Cell 21: EVAP and EGR Controls
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 near 8,000 Hertz at maximum engine load. DTC P0103 will be set if the signal from the MAF sensor is above the possible range of a normally operating MAF sensor.

### Conditions for Running the DTC

• | The engine is running.

• | Ignition voltage greater than 8.0 volts.

• | Throttle angle below 50%.

### Conditions for Setting the DTC

• | MAF signal frequency is above 11,500 Hertz (11.5 kHz).

• | The condition is present for 0.5 seconds.

### Action Taken When the DTC Sets

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

• | If equipped with traction control, the PCM will command the EBTCM via the serial data circuit to turn OFF traction control, and the EBTCM will illuminate the TRACTION OFF lamp.

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

### Conditions for Clearing the MIL/DTC

• | The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been 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 the scan tool.

### Diagnostic Aids

• | Check for the following conditions:

• | Poor connection at 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 fault.

Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals , and Connector Repairs in Wiring Systems.

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 numbers below refer to the step numbers 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 Electro-Magnetic Interference (EMI) related fault 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 OBD System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Start engine.
2. With the engine idling, monitor MAF FREQUENCY display on the scan tool engine data list.

Is MAF FREQUENCY below the specified value?

11.5 kHz (11,500 Hertz)

Go to Step 3

Go to Step 4

3 |

1. Turn the ignition on, and leave the engine off.
2. Review and record scan tool Fail Records data.
3. Operate vehicle within Fail Records conditions as noted.
4. Using a scan tool, monitor Specific DTC info for DTC P0103.

Does scan tool indicate DTC P0103 failed this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4 |

1. Turn the ignition off.
2. Disconnect the MAF sensor connector.
3. Start engine.
4. Using a scan tool, monitor MAF FREQUENCY.

Does scan tool indicate a MAF FREQUENCY at the specified value?

0 Hz

Go to Step 5

Go to Step 7

5 |

1. Test for a poor connection at the MAF sensor harness terminals.
2. If a poor connection is found, replace faulty terminal(s). Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals , and Connector Repairs in Wiring Systems..

Was a poor connection found?

--

Go to Step 10

Go to Step 6

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

1. Test MAF harness for incorrect routing

• | Near secondary ignition wires or coils:

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

2. If incorrect routing is found, correct harness routing.

Was a problem found?

--

Go to Step 10

Go to Step 8

8 |

1. Test MAF signal circuit terminal connections at the PCM.
2. If a poor connection is found, replace faulty terminal(s). Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals , and Connector Repairs in Wiring Systems..

Was a poor connection found?

--

Go to Step 10

Go to Step 9

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

1. Turn the ignition on, and leave the engine off.
2. Review and record scan tool Fail Records data.
3. Clear DTCs.
4. Operate vehicle within Fail Records conditions as noted.
5. Using a scan tool, monitor Specific DTC info for DTC P0103.

Does scan tool indicate DTC P0103 failed this ignition?

--

Go to Step 2

System OK