P0101
DTC P0101
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 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 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.
Conditions for Running the DTCs
* DTCs P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0128, P0335 or P0336 are not set.
* The engine speed is greater than 500 RPM.
* The engine coolant temperature (ECT) is between -7 and +125°C (+19 and +257°F).
* The intake air temperature (IAT Sensor 1) 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 ohms or greater on the ignition 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 Sensor 1 signal circuit will cause the MAF sensor signal to be skewed or erratic. Additionally, it may cause a rapid fluctuation in the IAT Sensor 1 parameter.
* 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 ((LFX)) [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
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 (Diagnostic Tools) Tools and Equipment.
Circuit/System Verification
1. Verify that the following DTCs are not set:
* 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 Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.
2. Verify that restrictions do not exist in the exhaust system. Refer to Restricted Exhaust Restricted Exhaust for further diagnosis.
3. Engine idling, observe the scan tool MAF Sensor parameter. The reading should be between 2.5-8.8 g/s depending on the engine coolant temperature (ECT) and barometric (BARO) pressure.
4. 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.
5. Verify the proper operation of the ECT sensor and IAT sensor 1. A skewed or stuck ECT sensor and IAT sensor 1 will cause the calculated models to be inaccurate and may cause this DTC to run/fail when it should not. Refer to Temperature Versus Resistance - Intake Air Temperature Sensor (Hitatchi Sensor) Specifications table.
6. Verify the proper operation of the MAP sensor. A skewed MAP sensor will cause the BARO value to be inaccurate. Refer to DTC P0106 (LF1, LFW, or LFX) P0106 for further diagnosis.
7. 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:
* 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 B75C Multifunction Intake Air Sensor element for contamination.
2. Ignition OFF, disconnect the harness connector at the B75C Multifunction Intake Air Sensor.
3. Ignition OFF, all vehicle systems OFF, this may take up to 2 min, test for less than 5 ohms between the ground circuit terminal 7 and ground.
• 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 5 and ground.
• 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 6 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 K20 engine control module.
Note: If the signal circuit is shorted to a voltage the ECM or the sensor may be damaged.
• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 engine control module.
6. Ignition OFF, connect the leads of the J 38522 - Variable Signal Generator as follows:
* Red lead to the signal circuit terminal 6 at the harness connector
* Black lead to ground
* Battery voltage supply lead to B+
7. Set the J 38522 - Variable Signal Generator to the following specifications.
* Signal switch to 5 V
* Duty Cycle switch to 50 % (Normal)
* Frequency switch to 5 KHz
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 parameter is not within the specified range, replace the K20 engine control module.
9. If all other circuits test normal, test or replace the B75C Multifunction Intake Air Sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Engine Coolant Temperature Sensor Replacement Service and Repair
* Mass Airflow Sensor with Intake Air Temperature Sensor Replacement Service and Repair for multifunction intake air sensor replacement.
* Control Module References Control Module References for ECM replacement, setup, and programming