Circuit Description
The mass air flow (MAF) sensor is an air flow meter that measures the amount of air entering the engine. The PCM uses the MAF sensor frequency signal in order to provide the correct fuel delivery for a wide range of engine speeds and loads. A small quantity of air entering the engine indicates deceleration or idle. A large quantity of air entering the engine indicates an acceleration or high load situation. The MAF sensor has an ignition 1 voltage circuit, a ground circuit and a signal circuit. The PCM applies a voltage to the sensor on the signal circuit. The sensor uses the voltage in order to produce a frequency based on inlet air flow through the sensor bore. The frequency will vary within a range of around 2,000 Hertz at idle to about 10,000 Hertz at maximum engine load. DTC P0103 will set if the PCM detects a frequency signal higher than the possible range of a normally operating sensor.
Conditions for Running the DTC
| • | The engine is running. |
| • | The IAC position is greater than 2 counts. |
| • | The Ignition 1 signal is greater than 8 volts. |
| • | The above conditions are present for greater than 0.5 second. |
Conditions for Setting the DTC
The MAF sensor frequency signal is greater than 11,500 Hertz.
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp during the second consecutive trip in which the diagnostic has been run and failed. |
| • | The PCM will store the conditions present when the DTC set as Freeze Frame/Failure Records . |
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. |
| • | Use the scan tool in order to clear the DTCs. |
Diagnostic Aids
| • | Water entering the air intake system that reaches the MAF sensor could cause this DTC to set. The water rapidly cools the hot sensing elements in the sensor causing a false indication of excessive air flow. Inspect the following areas for evidence of water intrusion: |
| - | The AIR system |
| - | The air induction system |
| • | A poor connection in the ignition 1 voltage circuit of the MAF sensor can cause a DTC P0103 to set. |
| • | If you suspect the vehicle condition may be related to aftermarket accessories, refer to Checking Aftermarket Accessories in Wiring Systems. |
| • | If the condition is intermittent, refer to Intermittent Conditions . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step tests for Electromagnetic Interference (EMI) on the signal circuit of the MAF sensor. A frequency reading with the MAF sensor disconnected indicates an EMI related fault or a poor connection. Disconnecting the MAF sensor may set additional related DTCs.
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This step eliminates any conditions which can cause a DTC to set with a normally operating MAF sensor.
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls ? | -- | Go to Step 2 | |||||||||
2 |
Does the DTC fail this ignition? | -- | Go to Step 3 | Go to Diagnostic Aids | ||||||||
Does the scan tool display the specified value? | 0 Hz | Go to Step 5 | Go to Step 4 | |||||||||
Inspect the harness of the MAF sensor for incorrect routing at the following components:
Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 6 | |||||||||
5 | Inspect for poor connections at the harness connector of the MAF sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 7 | ||||||||
6 | Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 8 | ||||||||
7 | Replace the MAF sensor. Refer to Mass Airflow Sensor Replacement . Did you complete the replacement? | -- | Go to Step 9 | -- | ||||||||
8 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 9 | -- | ||||||||
9 |
Does the DTC run and pass? | -- | Go to Step 10 | Go to Step 2 | ||||||||
10 | With a scan tool, observe the stored information in Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||||||
