P0101
DTC P0101 (Without Supercharger)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P0101
- Mass Air Flow (MAF) Sensor Performance
Diagnostic Fault Information
Typical Scan Tool Data
Circuit Description
The engine control module (ECM) uses the following information to calculate an expected airflow rate:
* The throttle position (TP)
* The barometric pressure (BARO)
* The manifold absolute pressure (MAP)
* The intake air temperature (IAT)
* The engine RPM
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 (TP) sensors. This is an explicit model-based diagnostic containing separate models for the intake system.
The estimates of MAF, MAP, and TP obtained from this system of models and calculations are then compared to the actual measured values from the MAF, MAP, and the TP sensors and to each other to determine the appropriate DTC to fail.
Conditions for Running the DTC
* DTCs P0102, P0103, P0107, P0108, P0111, P0112, P0113, P0116, P0117, P0118, P0128, P0335, P0336 are not set.
* The engine speed is between 450-5,750 RPM.
* The intake air temperature is between -20 and +125°C (-4 and +257°F).
* The engine coolant temperature is between -20 and +125°C (-4 and +257°F).
* This 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 TP sensors is not within range of the calculated airflow that is derived from the system of models for more than 0.5 s.
Action Taken When the DTC Sets
DTC P0101 is Type B DTC.
Conditions for Clearing the MIL/DTC
DTC P0101 is Type B DTC.
Diagnostic Aids
* A steady or intermittent high resistance of 15 ohms or greater on the ignition 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.
* 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 Temperature Versus Resistance.
* 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 (LS3) [1][2]Electrical DiagramsEngine Controls Schematics (LS7) [1][2]Electrical DiagramsEngine Controls Schematics (LS9) [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views 5 Bow Lowered Switch (CM7)
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Special Tools
J 38522 - Variable Signal Generator
For equivalent regional tools, refer to Special Tools Tools and Equipment.
Circuit/System Verification
1. If you were sent here from DTC P0068, P0106, P0121, or P1101 refer to Circuit/System Testing - step 1.
2. Ignition ON.
3. Verify the scan tool TB Idle Airflow Compensation parameter is less than 90 %.
• 90 % or greater
Refer to Throttle Body Cleaning Procedures.
• If less than 90 %
4. Verify the scan tool TP Sensors 1 and 2 Agree/Disagree parameter displays Agree while performing the Throttle Sweep Test with a scan tool.
• If Disagree
Refer to DTC P0120-P0123, P0220, P0222, P0223, or P2135 (Without Supercharger) DTC P0120-P0123, P0220, P0222, P0223, or P2135 (Supercharger) for further diagnosis.
• If Agree
5. Determine the current vehicle testing altitude.
6. Verify the scan tool MAP Sensor pressure parameter is within the range specified in the Altitude Versus Barometric Pressure Altitude Versus Barometric Pressure table.
• The MAP Sensor pressure is not in range
Refer to DTC P0106 (Without Supercharger) DTC P0106 (Supercharger) for further diagnosis.
• The MAP Sensor pressure is within range
7. Engine idling, verify the scan tool MAP Sensor pressure parameter is between 26-52 kPa (3.8-7.5 psi) and changes with accelerator pedal input.
• If not between 26-52 kPa (3.8-7.5 psi) or does not change
Refer to DTC P0106 (Without Supercharger) DTC P0106 (Supercharger) for further diagnosis.
• If between 26-52 kPa (3.8-7.5 psi) and changes
8. Verify the scan tool MAF Sensor g/s parameter changes smoothly and gradually as the engine speed is increased and decreased while performing the actions listed below.
1. Engine idling
2. Perform the scan tool snapshot function.
3. Increase the engine speed slowly to 3,000 RPM and then back to idle.
4. Exit from the scan tool snapshot and review the data.
5. Observe the MAF Sensor parameter frame by frame with a scan tool.
• The MAF Sensor parameter does not change smoothly and gradually
Refer to Circuit/System Testing - step 1.
• The MAF Sensor parameter changes smoothly and gradually
9. 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 data.
10. Verify a DTC does not set.
• If any DTC sets
Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.
• If no DTCs set
11. All OK
Circuit/System Testing
Note: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
1. Verify the integrity of the entire air induction system by inspecting for the following conditions:
* Loose clamps, cracks, or other damage in the air intake duct system
* Splits, kinks or improper connections at the vacuum hoses
* Vacuum leaks at the intake manifold and throttle body
* A dirty, restricted, or deteriorating air filter element
* A leaking, loose, disconnected, or cracked positive crankcase ventilation (PCV) valve, pipe, or seal
* A collapsed, restricted, or collapsed air intake duct
* A misaligned or damaged air intake duct
* Any objects blocking the air inlet probe of the MAF/IAT sensor
* Any contamination or debris on the sensing elements in the probe of the MAF/IAT sensor
* A cracked or damaged MAF sensor housing
* Any water intrusion in the induction system
* Any snow or ice build-up at the air cleaner, MAF or MAP sensors in cold climates
* Any intake manifold leak
* A MAP sensor seal that is leaking, missing, or damaged
* Improperly installed components
* An Intake Manifold Resonator with a leaking seal, or a cracked or broken housing
• If a condition exists
Repair or replace component as appropriate.
• If no condition exists
2. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B75B mass air flow /intake air temperature sensor. It may take up to 2 minutes for all vehicle systems to power down.
3. Test for less than 2 ohms between the ground circuit terminal B and ground.
• If 2 ohms or greater
1. Ignition OFF.
2. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 2 ohms
4. Ignition ON, verify a test lamp illuminates between the ignition voltage circuit terminal C and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF.
2. Test for less than 2 ohms in the ignition voltage circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF.
2. Test for infinite resistance between the ignition voltage circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for greater than 2 ohms between the ignition voltage circuit terminal C and ground.
• If less than 2 ohms, repair the short to ground on the circuit.
• If greater than 2 ohms, test all the components connected to the circuit and repair or replace as necessary.
• If the test lamp illuminates
5. Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal A and ground.
• If less than 4.8 V
1. Ignition OFF, disconnect the X1 harness connector at the K20 engine control module.
2. Test for infinite resistance between the signal circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the signal circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K20 engine control module.
• If greater than 5.2 V
1. Ignition OFF, disconnect the X1 harness connector at the K20 engine control module, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K20 engine control module.
• If between 4.8-5.2 V
6. Ignition OFF, connect the red lead of the J 38522 - variable signal generator to the signal circuit terminal A at the harness connector. Connect the battery voltage supply to B+, and the black lead to ground.
7. Set the J 38522 - variable signal generator to the following specifications.
* Signal switch to 5 V
* Frequency switch to 5 KHz
* Duty Cycle switch to Normal
8. Engine idling, observe the scan tool MAF Sensor parameter. The scan tool MAF Sensor parameter should be between 4,950-5,050 Hz.
• If not between 4,950-5,050 Hz.
If not between 4,950-5,050 Hz, replace the K20 engine control module.
• If between 4,950-5,050 Hz.
9. Test or replace the B75B mass air flow /intake air temperature sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Mass Airflow Sensor with Intake Air Temperature Sensor Replacement Service and Repair
* Control Module References Control Module References for engine control module replacement, programming, and setup