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DTC P0101 - Without Special Tool

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 provides an overview of each diagnostic category.

DTC Descriptor

DTC P0101: Mass Air Flow (MAF) Sensor Performance

Diagnostic Fault Information

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

Ignition 1 Voltage

P0102

P0101

P0102

-

P0101, P0103

MAF Sensor Signal

P0102

P0102

P0102

P0102

P0101, P0103, P1101

Ground

-

P0102

P0102

-

P0102

Circuit Description

The intake flow rationality diagnostic provides the within-range rationality check for the mass air flow (MAF), manifold absolute pressure (MAP), and the throttle position sensors. This is an explicit model-based diagnostic containing 4 separate models for the intake system.

    • The throttle model describes the flow through the throttle body and is used to estimate the MAF through the throttle body as a function of barometric pressure (BARO), throttle position sensors, intake air temperature (IAT), and estimated MAP. The information from this model is displayed on the scan tool as the MAF Performance Test parameter.
    • The first intake manifold model describes the intake manifold and is used to estimate MAP as a function of the MAF into the manifold from the throttle body and the MAF out of the manifold caused by engine pumping. The flow into the manifold from the throttle uses the MAF estimate calculated from the above throttle model. The information from this model is displayed on the scan tool as the MAP Performance Test 1 parameter.
    • The second intake manifold model is identical to the first intake manifold model except that the MAF sensor measurement is used instead of the throttle model estimate for the throttle air input. The information from this model is displayed on the scan tool as the MAP Performance Test 2 parameter.
    • The fourth model is created from the combination and additional calculations of the throttle model and the first intake manifold model. The information from this model is displayed on the scan tool as the Throttle Position Sensors Performance Test parameter.

The estimates of MAF and MAP obtained from this system of models and calculations are then compared to the actual measured values from the MAF, MAP, and the throttle position sensors and to each other to determine the appropriate DTC to fail. The following table illustrates the possible failure combinations and the resulting DTC or DTCs.

Scan Tool Diagnostic Test Results

MAF Performance Test

MAP Performance Test 1

MAP Performance Test 2

Throttle Position Sensors Performance Test

DTCs Passed

DTCs Failed

-

-

OK

OK

P0101, P0106, P0121, P1101

None

OK

OK

Malfunction /Fault

OK

P0101, P0106, P0121, P1101

None

Malfunction /Fault

OK

Malfunction /Fault

OK

P0106, P0121, P1101

P0101

OK

Malfunction /Fault

Malfunction /Fault

OK

P0101, P0121, P1101

P0106

Malfunction /Fault

Malfunction /Fault

Malfunction /Fault

OK

P0121, P1101

P0101, P0106

-

-

OK

Malfunction /Fault

P0101, P0106, P1101

P0121

OK

OK

Malfunction /Fault

Malfunction /Fault

P0101, P0106, P0121, P1101

None

Malfunction /Fault

OK

Malfunction /Fault

Malfunction /Fault

P0101, P0106, P0121

P1101

-

Malfunction /Fault

Malfunction /Fault

Malfunction /Fault

P0101, P0106, P0121

P1101

OK

OK

Malfunction /Fault

OK

-

P0102

Conditions for Running the DTCs
    • DTCs P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0128, P0335 or P0336 are not set.
    • The engine is running.
    • The engine coolant is between 69-127°C (156-261°F).
    • The intake air temperature is between -20 and +125°C (-4 and +257°F).
    • The DTC runs continuously when the above conditions are met.

Conditions for Setting the DTC

The engine control module (ECM) detects that the actual measured airflow from the MAF, MAP, and throttle position sensors is not within range of the calculated airflow that is derived from the system of models for greater than 2 s.

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.

Diagnostic Aids
    • A steady or intermittent high resistance of 15 Ω or greater on the ignition 1 voltage circuit will cause the MAF sensor signal to be increased by as much as 60 g/s.
    • 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 cause the MAF sensor signal to be skewed or erratic. Additionally, it may cause a rapid fluctuation in the IAT Sensor parameter.
    • A skewed or stuck engine coolant temperature (ECT) or IAT sensor will cause the calculated models to be inaccurate and may cause this DTC to run when it should not. Refer to Temperature Versus Resistance - Engine Coolant Temperature Sensor or Temperature Versus Resistance - Intake Air Temperature Sensor .
    • Compare the MAF Sensor parameter to a known good vehicle, under various operating conditions.
    • Certain aftermarket air filters may cause this DTC to set.
    • Certain aftermarket air induction systems may cause this DTC to set.
    • Modifications to the air induction system may cause this DTC to set.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component 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

Control Module References for scan tool information

Circuit/System Verification
  1. Verify that the following DTCs are not set:
    2. • 5 V reference circuits
    • Camshaft position system performance
    • Engine controls ignition relay circuits
    • Ignition circuits--Body control module (BCM)
    ⇒If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
  2. Verify that restrictions do not exist in the exhaust system. Refer to Restricted Exhaust .
  3. A wide open throttle (WOT) acceleration from a stop should cause the MAF Sensor parameter on the scan tool to increase rapidly. This increase should be from 2-8 g/s at idle to greater than 180 g/s at the time of the 1-2 shift.
  4. Verify the proper operation of the ECT and IAT sensors. A skewed or stuck ECT or IAT sensor will cause the calculated models to be inaccurate and may cause this DTC to run when it should not. Refer to Temperature Versus Resistance - Intake Air Temperature Sensor .
  5. Verify the proper operation of the MAP sensor. A skewed MAP sensor will cause the BARO value to be inaccurate. Refer to Diagnostic Trouble Code (DTC) List - Vehicle for DTC P0106.
  6. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing
  1. Verify the integrity of the entire air induction system by inspecting for the following conditions:
    2. • Any damaged components
    • Loose or improper installation
    • An air flow restriction
    • Any vacuum leaks
    • Water intrusion
    • In cold climates, inspect for any snow or ice buildup
    • Inspect the B75B mass air flow/intake air temperature sensor element for contamination.
  2. Ignition OFF, disconnect the harness connector at the B75B mass air flow/intake air temperature sensor.
  3. Ignition OFF, all vehicle systems OFF, this may take up to 2 min, test for less than 5 Ω between the ground circuit terminal B and ground.
    4. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal C and ground.
    5. ⇒If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
    ⇒If the circuit tests normal and the fuse is open, test all the components connected to the circuit and repair or replace as necessary.
  5. Ignition ON, test for 4.8-5.2 V between the signal circuit terminal A and ground.
    6. ⇒If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
    ⇒If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
  6. If all other circuits test normal, test or replace the B75B mass air flow/intake air temperature sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

    •  Engine Coolant Temperature Sensor Replacement : LF1 or LFW
    •  Mass Airflow Sensor with Inlet Air Temperature Sensor Replacement
    • Control Module References for ECM replacement, setup, and programming
   


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