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 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), TP, 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 TP 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 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 ohm 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 Electrical Specifications.
* 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 [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Connector Views
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.
Circuit/System Verification
1. If you were sent here from DTC P0068, P0106, P0121, or P1101 refer to Circuit/System Testing.
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 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 P0106 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 P0106 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.
• 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:
* Improperly installed components
* Collapsed, restricted, or damaged components
* Loose clamps, cracks, or other damage
* An air flow restriction
* Restricted air filter
* Splits, kinks, leaks, or improper connections at the vacuum hoses
* Vacuum leaks at the intake manifold, MAP sensor, and throttle body
* Water intrusion
* In cold climates, inspect for any snow or ice buildup
* Inspect the B75B mass air flow sensor element for contamination
• If a condition is found
If a condition is found, repair or replace component as appropriate.
• No condition found
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 ohm between the ground circuit terminal B and ground.
• If 2 ohm or greater
1. Ignition OFF.
2. Test for less than 2 ohm in the ground circuit end to end.
• If 2 ohm or greater, repair the open/high resistance in the circuit.
• If less than 2 ohm, repair the open/high resistance in the ground connection.
• If less than 2 ohm
4. Ignition ON, verify a test lamp illuminates between the ignition 1 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 ohm in the ignition 1 voltage circuit end to end.
• If 2 ohm or greater, repair the open/high resistance in the circuit.
• If less than 2 ohm, 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 1 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 ohm between the ignition 1 voltage circuit terminal C and ground.
• If less than 2 ohm, repair the short to ground on the circuit.
• If greater than 2 ohm, refer to DTC P0685, P0689, P0690, or P1682 P0685 to verify the operation of the Powertrain Ign 1 Relay.
• 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 harness connector at the K20 ECM.
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 ohm in the signal circuit end to end.
• If 2 ohm or greater, repair the open/high resistance in the circuit.
• If less than 2 ohm, replace the K20 ECM.
• If greater than 5.2 V
1. Ignition OFF, disconnect the harness connector at the K20 ECM, 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 ECM.
• If between 4.8-5.2 V
6. Ignition OFF, connect the red lead of the J 38522 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 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 ECM.
• If between 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 (LSA) Service and Repair
* Control Module References Control Module References for engine control module replacement, programming, and setup