P0101
DTC P0101 or P1101
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 Descriptors
DTC P0101
- Mass Air Flow (MAF) Sensor Performance
DTC P1101
- Intake Air Flow System Performance
Diagnostic Fault Information
Typical Scan Tool Data
Circuit Description
The intake flow rationality diagnostic provides the within-range rationality check for the mass air flow (MAF), the 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, the MAP, and the TP 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.
Conditions for Running the DTC
* DTCs P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0128, P0335, P0336, P0401, P0405, and P1404 are not set.
* The engine speed is between 500-5,000 RPM.
* The IAT is between -7 and +125°C (+19 and +257°F).
* The engine coolant temperature (ECT) is between 70-125°C (158-257°F).
* This DTC runs continuously within the enabling conditions.
Conditions for Setting the DTC
P0101
The engine control module (ECM) detects that the difference between the measured MAF and the MAP performance test 2 is greater than 25 g/s for greater than 0.5 s.
P1101
The engine control module (ECM) detects that the actual measured airflow from the MAF, the MAP, and the TP sensors is not within range of the calculated airflow that is derived from the system of models for greater than 0.5 s.
Action Taken When the DTC Sets
DTCs P0101 and P1101 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0101 and P1101 are Type B DTCs.
Diagnostic Aids
* A steady or intermittent high resistance of 25 ohm or greater on the ignition voltage circuit will cause the MAF sensor values to be skewed high by up to 30 g/s.
* 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).
* 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.
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 (Programming and Relearning) for scan tool information
Special Tools
J 38522 Variable Signal Generator
Circuit/System Verification
1. Verify that the following DTCs are not set: P0641 or P0651.
• If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code (DTC) List - Vehicle) for diagnosis of DTC P0641 or P0651.
2. Verify that restrictions do not exist in the exhaust system. Refer to Restricted Exhaust (Restricted Exhaust).
3. Engine operating at idle, observe the scan tool MAF Sensor parameter. The reading should be between 1,700-3,800 Hz, depending on the ECT.
4. 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 3-8 g/s at idle to 190 g/s or more at the time of the 1-2 shift.
5. 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 (Temperature Versus Resistance).
6. 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 (Diagnostic Trouble Code (DTC) List - Vehicle) for DTC P0106.
7. A skewed MAF sensor, intake air flow restriction or intake air flow leak after the MAF sensor may cause the calculated g/s and MAF g/s parameters to disagree. Road test the vehicle while observing both parameters under various engine loads.
8. 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.
Circuit/System Testing
1. Verify the integrity of the entire air induction system by inspecting for the following conditions:
* Any damaged components
* Loose or improper installation
* An air flow restriction
* An air flow leak
* Any vacuum leak
* In cold climates, inspect for any snow or ice buildup.
* Water intrusion
* Inspect the MAF sensor elements for contamination.
2. Ignition OFF, disconnect the harness connector at the MAF/IAT sensor.
3. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 5 ohm between the ground circuit terminal C and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
4. Ignition ON, verify a test lamp illuminates between the ignition circuit terminal B and ground.
• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
5. Ignition ON, test for 4.8-5.2 V between the signal circuit terminal A and ground.
• 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 ECM.
• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
6. Ignition OFF, connect the red lead of the J 38522 to the signal circuit terminal A at the MAF/IAT sensor harness connector. Connect the battery voltage supply to B+. Connect the black lead to ground.
7. Set the J 38522 signal to 5 V, the frequency to 5K, and the Duty Cycle 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 the MAF Sensor parameter is not within the specified range, replace the ECM.
9. If all circuits test normal, test or replace the MAF/IAT sensor.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Mass Airflow Sensor with Intake Air Temperature Sensor Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming