GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2004 🢒 Vibe - FWD 🢒 DTC 🢒 DTC P0100

Circuit Description

The DTC P0100 Mass Air Flow (MAF) Sensor Circuit 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 thermistor 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.

Conditions for Setting the DTC
    • An open or a short is detected in the MAF sensor signal circuit when the engine speed is less than 4,000 RPM.
    • The condition is present for at least 3 seconds.

Action Taken When the DTC Sets
    • The PCM illuminates the malfunction indicator lamp (MIL) after 2 consecutive ignition cycles in which the diagnostic runs with the fault active.
    • 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 PCM turns OFF the MIL after 3 consecutive trips without a fault.
    • The PCM clears a History DTC 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.

  1. The Diagnostic System Check-Engine Controls 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.

    2.

  2. This step checks for a high input signal from the mass air flow (MAF) sensor.

    3.

  3. This step checks for a low input signal from the MAF sensor.

    4.

  4. This step is looking for MAF sensor output on the MAF signal high circuit. Air movement around the sensor's hot wire element can cause some fluctuation in the voltage being measured.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

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 7

Go to Step 3

3

Observe the MAF sensor parameters the scan tool.

Is the MAF sensor less than or equal to the specified value?

0.45 g/s

Go to Step 5

Go to Step 4

4
  1. Clear the DTC Information with the scan tool.
  2. Operate the vehicle within the Freeze Frame conditions as specified.

Does a DTC P0100 set?

--

Go to Step 2

Go to Intermittent Conditions

5
  1. Turn OFF the ignition.
  2. Disconnect the MAF sensor electrical connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the ignition positive voltage circuit with a test lamp connected to ground.

Is the test lamp illuminated?

--

Go to Step 6

Go to Step 10

6

  1. Turn OFF the ignition.
  2. Connect the MAF sensor electrical connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Backprobe the MAF signal high circuit at the PCM with a DMM connected to ground.

Is the MAF signal high voltage within the specified range?

0.5-3.0 V

Go to Step 11

Go to Step 12

7
  1. Turn OFF the ignition.
  2. Disconnect the MAF sensor electrical connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp from B+ to the MAF signal low circuit.

Does the test lamp illuminate?

--

Go to Step 8

Go to Step 9

8

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 13

Go to Step 15

9
  1. Test for an open in the MAF sensor signal low circuit.
  2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct a condition?

--

Go to Step 18

Go to Step 14

10

Repair the open in the MAF sensor ignition positive voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 18

--

11
  1. Remove the MAF sensor from the air cleaner housing. Refer to Mass Airflow Sensor Replacement .
  2. Continue to backprobe the MAF signal high circuit at the PCM with the DMM.
  3. Observe the voltage on the MAF signal high circuit while blowing gently into the MAF sensor orifice.

Did the signal high circuit voltage increase when blowing air into the sensor orifice?

--

Go to Step 14

Go to Step 15

12
  1. Test for an open or a short to ground in the MAF signal high circuit.
  2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct a condition?

--

Go to Step 18

Go to Step 15

13
  1. Test for a short to voltage in the MAF signal high circuit.
  2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct a condition?

--

Go to Step 18

Go to Step 17

14
  1. Test for an intermittent or a poor electrical connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
  2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct a condition?

--

Go to Step 18

Go to Step 17

15
  1. Test for an intermittent or a poor electrical connection at the MAF sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
  2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct a condition?

--

Go to Step 18

Go to Step 16

16

Replace the MAF sensor. Refer to Mass Airflow Sensor Replacement .

Did you complete the replacement?

--

Go to Step 18

--

17

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 18

--

18
  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

--

Go to Step 19

Go to Step 2

19

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK