Circuit Description
The DTC P0103 Mass Air Flow (MAF) Sensor Circuit High Voltage diagnostic detects an out of range sensor signal. The MAF sensor measures the changes in the intake air volume that result from the changes in throttle opening and air density. Air flow measurements are used by the powertrain control module (PCM) in order to determine engine fueling requirements.
The MAF sensor is a hot wire design. A platinum hot wire and a thermister are located in the intake air bypass passage of the MAF sensor housing. The temperature of the platinum hot wire is affected by exposure to air flow and by exposure to air temperature. The platinum hot wire is maintained at a set temperature by controlling the current flow through the wire. The MAF sensor converts the changes in current flow to a voltage signal. The voltage signal from the MAF sensor enables the PCM to detect changes in air density and changes in air volume.
Conditions for Running the DTC
| • | The ignition is ON or the engine is running. |
| • | DTC P0103 runs continuously once the above condition has been met. |
Conditions for Setting the DTC
| • | The MAF sensor signal is more than 4.9 volts. |
| • | The condition is present for at least 3 seconds. |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL). |
| • | The PCM records the operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame buffer. |
| • | The PCM enters the Fail-Safe Function and operates with the ignition timing fixed at 5 degrees before top dead center (BTDC). |
Conditions for Clearing the MIL/DTC
| • | The MIL turns OFF after 3 consecutively passing cycles without a fault present. |
| • | A History DTC will clear after 40 consecutive warm-up cycles without a fault. |
| • | Perform the scan tool clear DTC Information Function in order to clear the DTC. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The Diagnostic System Check - Vehicle prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
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This step checks for a high input signal from the mass air flow (MAF) sensor.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | ||||
Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | ||
Select the MAF sensor parameter on the scan tool. Is the MAF sensor value more than or equal to the specified value? | 185.0 g/s | Go to Step 4 | Go to Step 3 | |
3 |
Does a DTC P0103 set? | -- | Go to Step 4 | Go to Intermittent Conditions |
4 |
Does the test lamp illuminate? | -- | Go to Step 5 | Go to Step 6 |
5 | Measure the voltage of the MAF signal high circuit at the MAF sensor connector with a DMM connected to ground. Is the MAF signal high circuit voltage more than the specified value? | 0.2 V | Go to Step 7 | Go to Step 9 |
6 |
Did you find and correct a condition? | -- | Go to Step 12 | Go to Step 8 |
7 |
Did you find and correct a condition? | -- | Go to Step 12 | Go to Step 11 |
8 |
Did you find and correct a condition? | -- | Go to Step 12 | Go to Step 11 |
9 |
Did you find and correct a condition? | -- | Go to Step 12 | Go to Step 10 |
10 | Replace the MAF sensor. Refer to Mass Airflow Sensor Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- |
11 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- |
12 |
Does the DTC run and pass? | -- | Go to Step 13 | Go to Step 2 |
13 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
