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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2007 🢒 TopKick C-Series (Conventional) C4/C5 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC P0101

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provide an overview of each diagnostic category.

DTC Descriptor

DTC P0101: Mass Air Flow (MAF) Sensor Performance

Diagnostic Fault Information

Circuit

Short to Ground

Open

Short to Voltage

MAF Sensor Signal Circuit

P2564

P2564

P2565

MAF Sensor Ground Circuit

--

P2564

--

Typical Scan Tool Data

MAF Sensor

Circuit

Short to Ground

Open

Short to Voltage

Operating Conditions: Engine Running

Parameter Normal Range: 15-35 g/s

MAF Sensor Signal Circuit

0.0 g/s

0.0 g/s

496.2 g/s

MAF Sensor Ground Circuit

--

496.2 g/s

--

Circuit/System 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 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 compares the actual MAF sensor voltage signal to a predicted MAF value. This comparison will determine if the signal is stuck, or is too low or too high for a given operating condition.

Conditions for Running the DTC
    • DTC P0016, P0027, P0079, P0080, P0101, P0102, P0103, P0112, P0113, P0116, P0117, P0118, P0126, P0201, P0202, P0203, P0204, P0205, P0206, P0261, P0270, P0273, P0276, P02E2, P02E3, P02E7, P02E8, P02E9, P0335, P0336, P0401, P0403, P0404, P0409, P042E, P0500, P0506, P0507, P0602, P0642, P0643, P0652, P0653, P0698, P0699, P1125, P1293, P2002, P2146, P2147, P2148, P2149, P2150, P2151, P2227, P2228, P2229, P2454, P2455, P268A are not set.
    • The following conditions are met:

Condition 1

       - The barometric pressure (BARO) is between 75-120 kPa.
       - The intake air temperature (IAT) is between -7 and +120°C (19.4-248°F).
       - The vehicle speed is between 0-255 mph.
       - The above conditions are met for 6 seconds.

Condition 2

       - The battery voltage is between 10-16 volts.
       - The ignition switch is ON for longer than 2 seconds.
       - The engine is running.
       - The accelerator pedal position is less than 100 percent longer than 2 seconds.
       - The engine speed is less than 2550 RPM.
       - Engine coolant temperature (ECT) is between 55-102°C (131-215.6°F).

Condition 3

       - The exhaust brake is commanded OFF.
       - The intake throttle position is less than 55 percent.
       - The differential pressure is between -2 and +60 kPa.
       - The DPF status is NOT during regeneration.
    • The VNT control mode is Normal.
    • The above items are met for 5 seconds.

Conditions for Setting the DTC

The ECM detects that the MAF sensor is not within a predetermined range of the calculated MAF value for greater than 15 seconds.

Action Taken When the DTC Sets

DTC P0101 is a Type B DTC.

Conditions for Clearing the MIL/DTC

DTC P0101 is a Type B DTC.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Controls Component Views
    •  Engine Control Module Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Diagnostic Aids
    • A steady or intermittent high resistance of 15 ohms or greater on the ignition 1 voltage circuit will cause the MAF sensor signal to be increased by as much as 60 g/s. To pinpoint this condition, perform a voltage drop test on the circuit.
    • Any type of contamination on the MAF sensor heating elements will degrade the proper operation of the sensor. Certain types of contaminants act as a heat insulator, which will impair the response of the sensor to airflow changes. Water or snow can create the opposite effect and cause the signal to increase rapidly.
    • Depending on the current ambient temperature and the vehicle operating conditions, a MAF sensor signal circuit that is shorted to the IAT signal circuit will increase or decrease the MAF sensor signal that is interpreted by the ECM. Additionally, it may cause a rapid fluctuation in the IAT Sensor parameter.

Circuit/System Verification
  1. If DTC P0102, P0103, or P0405 are set, diagnose these DTC first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle for further information.
  2. Verify the integrity of the entire air induction system by inspecting for the following conditions:
    3. • Restrictions in the MAF air induction system and the turbocharger system
    • Restrictions in the exhaust system--Refer to Restricted Exhaust .
    • Leaks at the MAF/IAT sensor O-ring seal
    • Cracked or damaged MAF sensor housing
    • Restricted intake air duct or a dirty air filter element
    • Debris blocking the air sensing filaments of the MAF sensor
    • Snow or ice build-up in cold climates.

Circuit/System Testing

Important: All electrical components and accessories must be turned OFF and allowed to power down.

You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

  1. Ignition OFF, disconnect the harness connector at the MAF/IAT sensor.
  2. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit terminal 4 and ground.
    3. ⇒If greater than 5 ohms, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  3. Ignition ON, verify a test lamp illuminates between the ignition circuit terminal 3 and ground.
    4. ⇒If test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
  4. Ignition ON, verify the scan tool MAF sensor parameter is less than 0 g/s.
    5. ⇒If greater than 0 g/s, test the signal circuit terminal 5 for a short to voltage. If the circuit tests normal, replace the ECM.
  5. Install a 3A fused jumper wire between the signal circuit terminal 5 and the IAT signal circuit terminal 2. Verify the scan tool MAF sensor parameter is greater than 500 g/s.
    6. ⇒If less than 500 g/s, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
  6. Test for air leaks at the manifold absolute pressure (MAP) sensor seal.
    7. ⇒If a leaking sensor seal is verified, repair as necessary.
  7. Test the charge air cooler system for leaks.
    8. ⇒If a charge air cooler leak is found, repair as necessary.

    Important: Do NOT drain the coolant at this time.

  8. Remove the air inlet tube to intake manifold. Perform steps 1-15.
  9. Visually inspect the EGR valve and verify the valve is in the closed position.
    10. ⇒If the EGR valve is not in the closed position, replace the EGR valve.
    ⇒If the EGR valve inspection is normal, replace the MAF/IAT sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Mass Airflow Sensor/Intake Air Temperature Sensor Replacement
    •  Exhaust Gas Recirculation Valve Replacement
    •  Control Module References for ECM replacement, setup, and programming