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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2004 🢒 TopKick C-Series (Conventional) C4/C5 🢒 Engine 🢒 Engine Controls - 6.6L (LLY) 🢒 DTC P0101

Circuit Description

The mass air flow (MAF) sensor is an air flow meter that measures the amount of air entering the engine. The engine control module (ECM) uses the MAF sensor voltage signal to provide the correct fuel delivery for a reduction in emissions. The ECM uses the MAF sensor signal to control fuel delivery until a calibrated amount of engine air flow is attained. The MAF sensor has an ignition 1 voltage circuit, a signal circuit and a low reference circuit. The MAF sensor produces an output voltage based on the inlet air flow through the air induction system. This output voltage will display on the scan tool as a voltage parameter and as a grams per second (g/s) parameter. The ECM will calculate a predicted MAF value. The ECM compares the actual MAF sensor voltage signal to the predicted MAF value. This comparison will determine if the signal is stuck, or is too low or too high for a given operating condition. If the ECM detects that the actual MAF sensor voltage signal is not within a predetermined range of the calculated MAF value, DTC P0101 sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0101 Mass Air Flow (MAF) Sensor Performance

Conditions for Running the DTC
    • DTC P0016, P0102, P0103, P0112, P0113, P0116, P0117, P0118, P0234, P0237, P0238, P0299, P0335, P0336, P0340, P0341, P0370, P0374, P2227, P2228, P2229 are not set.
    • The ignition 1 signal is between 9-18 volts.
    • The intake air temperature (IAT) is more than -20°C (-4°F).
    • The engine speed is less than 3,500 RPM.
    • The engine speed is steady within a range of 50 RPM.
    • The engine coolant temperature (ECT) is more than -20°C (-4°F).
    • The above conditions are met for more than 2 seconds.
    • DTC P0101 runs continuously within the enabling conditions.

Conditions for Setting the DTC

The ECM detects that the MAF sensor voltage signal is not within a predetermined range of the calculated MAF value for more than 12 seconds.

Action Taken When the DTC Sets - California
    • The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Action Taken When the DTC Sets - Federal
    • The control module stores the DTC information into memory when the diagnostic runs and fails.
    • The malfunction indicator lamp (MIL) will not illuminate.
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
    • The driver information center, if equipped, may display a message.

Conditions for Clearing the MIL/DTC - California
    • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Use a scan tool in order to clear the MIL and the DTC.

Conditions for Clearing the DTC - Federal
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
    • Use a scan tool in order to clear the MIL and the DTC.

Diagnostic Aids
    • Any unmetered air that enters the engine downstream of the MAF sensor may cause this DTC to set.
    • A short between the signal circuit of the MAF sensor and the signal circuit of the intake air temperature (IAT) sensor will skew the MAF sensor higher than normal at idle and less than normal at higher air flows.
    • A malfunctioning MAF sensor can cause excessive engine emissions.
    • The MAF display should increase from 24-50 g/s at idle to 320 g/s or more at the 2-3 shift during a wide-open throttle (WOT) acceleration. If not, inspect for a restriction in the induction system or the exhaust system.
    • If the vehicle condition is intermittent, refer to Inducing Intermittent Fault Conditions and Intermittent Conditions .

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check - Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Review the DTC information on the scan tool.

Is DTC P0405 set?

--

Go to DTC P0405

Go to Step 3

3
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4
  1. Turn OFF the ignition.
  2. Turn ON the ignition, with the engine OFF.
  3. Observe the MAF Sensor parameter with a scan tool.

Is the MAF Sensor parameter more than the specified value?

0.30 V

Go to Step 7

Go to Step 5

5
  1. Turn OFF the ignition.
  2. Inspect for air leaks in the following components:
    3. • The air induction system and the turbocharger system
    • The charge air cooler with a J 46091 Charge Air Cooler Tester
    • The mass air flow (MAF)/intake air temperature (IAT) sensor O-ring seal
    • The boost pressure sensor seal
    • An exhaust gas recirculation (EGR) valve gasket that is missing or damaged
  3. Inspect for the following conditions:
    4. • A cracked MAF sensor housing
    • An obstructed intake air duct or a dirty air filter element
    • Any debris that is blocking the air sensing filaments of the MAF sensor
    • Any water intrusion in the air induction system
    • A MAF sensor that is installed backwards
    • An EGR valve that is sticking.
    • A restricted exhaust system--Refer to Restricted Exhaust .

Did you find and correct the condition?

--

Go to Step  24

Go to Step 6

6
  1. Turn ON the ignition, with the engine OFF.
  2. Observe both the BARO parameter and the Boost Pressure Sensor parameter with a scan tool.

Is the difference between the sensors equal to or less than the specified value?

5 kPa

Go to Step 8

Go to DTC P2227

7
  1. Disconnect the MAF/IAT sensor.
  2. Observe the MAF Sensor parameter with a scan tool.

Is the MAF Sensor parameter more than the specified value?

0 V

Go to Step 14

Go to Step 8

8
  1. Connect the MAF/IAT sensor.
  2. Start the engine and allow it to idle.
  3. Observe the MAF Sensor parameter with a scan tool.
  4. Move the harness and the connector of the MAF/IAT sensor.

Does the movement of the harness or the connector affect the MAF Sensor parameter?

--

Go to Step 21

Go to Step 9

9
  1. Turn OFF the engine.
  2. Turn ON the ignition, with the engine OFF.
  3. Measure the battery voltage with a DMM.
  4. Disconnect the MAF/IAT sensor.
  5. Connect a test lamp between the ignition 1 voltage circuit of the MAF sensor and a good ground. Refer to Probing Electrical Connectors and Circuit Testing .
  6. Connect the DMM to the probe of the test lamp and a good ground. Refer to Measuring Voltage Drop and Circuit Testing .

Is the voltage within 1.5 volts of the specified value?

B+

Go to Step 10

Go to Step 18

10

Important: All electrical components and accessories must be turned OFF.

  1. Turn OFF the ignition for 60 seconds to allow the control modules to power down before proceeding.
  2. Measure the resistance from the low reference circuit of the MAF sensor to a good ground with a DMM. Refer to Circuit Testing .

Is the resistance less than the specified value?

5 ohms

Go to Step 11

Go to Step 12

11
  1. Turn ON the ignition, with the engine OFF.
  2. Connect a 3-amp fused jumper wire between the signal circuit of the MAF sensor and the signal circuit of the IAT sensor. Refer to Circuit Testing .
  3. Observe the MAF Sensor parameter with a scan tool.

Is the MAF Sensor parameter more than the specified value?

445 g/s

Go to Step 16

Go to Step 13

12
  1. Disconnect the engine control module (ECM).
  2. Test the MAF sensor low reference circuit for the following conditions:
    3. • A high resistance
    • An intermittent open
    •  Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 24

Go to Step 17

13
  1. Turn OFF the ignition.
  2. Disconnect the ECM.
  3. Test the MAF sensor signal circuit for the following conditions:
    4. • A high resistance or an intermittent open
    • A high resistance short to ground
    • A high resistance short to the low reference circuit of the MAF sensor or the IAT sensor

Did you find and correct the condition?

--

Go to Step 24

Go to Step 17

14

Important:: Disconnecting the ECM connectors may eliminate the short to voltage if the signal circuit is shorted to another ECM circuit.

  1. Turn OFF the ignition.
  2. Disconnect the ECM, C1 connector only.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the signal circuit of the MAF sensor to a good ground with a DMM. Refer to Circuit Testing .

Is the voltage more than the specified value?

0 V

Go to Step 19

Go to Step 15

15
  1. Turn OFF the ignition.
  2. Disconnect all of the ECM connectors.
  3. Measure the resistance from the signal circuit of the MAF sensor to all other circuits at all ECM connectors with a DMM. Refer to Circuit Testing .

Is the resistance less than the specified value?

∞ ohms

Go to Step 20

Go to Step 17

16

Test for shorted terminals, an intermittent and for a poor connection at the MAF/IAT sensor. Refer to Testing for Intermittent Conditions and Poor Connections , Repairing Connector Terminals , and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 24

Go to Step 22

17

Test for shorted terminals, an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 24

Go to Step 23

18

Repair the high resistance or the intermittent open in the MAF sensor ignition 1 voltage circuit. Refer to Wiring Repairs .

Did you complete the repair?

--

Go to Step 24

--

19

Repair the short to voltage in the MAF sensor signal circuit. Refer to Wiring Repairs .

Did you complete the repair?

--

Go to Step 24

--

20

Repair the circuits that are shorted together. Refer to Wiring Repairs s.

Did you complete the repair?

--

Go to Step 24

--

21

Repair the harness or the connections as necessary. Refer to Connector Repairs , Repairing Connector Terminals , and Wiring Repairs .

Did you complete the repair?

--

Go to Step 24

--

22

Replace the MAF/IAT sensor. Refer to Mass Airflow Sensor/Intake Air Temperature Sensor Replacement .

Did you complete the replacement?

--

Go to Step 24

--

23

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the replacement?

--

Go to Step 24

--

24
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 25

25

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK