P0101
DTC P0101
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
DTC Descriptor
DTC P0101
- Mass Air Flow (MAF) Sensor Circuit Performance
Diagnostic Fault Information
Circuit/System Description
The mass air flow (MAF) sensor is located in the air intake duct. The MAF sensor is an airflow meter that measures the amount of air that enters the engine. The MAF sensor uses a hot film that is cooled by air flowing past the sensing film as air enters the engine. The amount of cooling is proportional to the amount of the air flow. As the air flow increases, more current is required in order to maintain the hot film at a constant temperature. The engine control module (ECM) uses the MAF sensor in order to provide the correct fuel delivery for all operating conditions.
Conditions for Running the DTC
* Before the ECM can report DTC P0101 failed, DTCs P0010, P0013, P0020, P0023, P0040, P0100, P0102, P0103, P0111, P0112, P0113, P0121, P0122, P0123, P0221, P0222, P0223, P2088, P2089, P2090, P2091, P2092, P2093, P2094, P2095, P2227, P2228, or P2229 must run and pass.
* The engine is operating for greater than 1 second.
* The ignition voltage is greater than 10 volts.
* The ECM is not commanding fuel cut-off.
* The ECM detects greater than 150 revolutions of the crankshaft.
* DTC P0101 runs continuously once the above conditions are met.
Conditions for Setting the DTC
The ECM detects that the MAF sensor signal is greater or less than the calculated air flow based on engine load and engine speed.
Action Taken When the DTC Sets
DTC P0101 is a Type B DTC.
Conditions for Clearing the DTC
DTC P0101 is a Type B DTC.
Diagnostic Aids
* Inspect the harness of the MAF sensor to verify that it is not routed too close to the following components:
- The secondary ignition wires or coils
- Any solenoids
- Any relays
- Any motors
* Inspect the hydro-carbon (HC) absorber in the air cleaner assembly for ruptures that would leak charcoal into the air intake, contaminating the sensing element.
* Inspect for any contamination, water intrusion, or debris on the sensing elements of the MAF sensor. If debris is present, clean the sensor. If the sensor cannot be cleaned, replace the sensor.
* A high resistance may cause a driveability concern before this DTC sets.
Reference Information
Schematic Reference
Engine Controls Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Air Intake System Description (Air Intake System Description)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Special Tools
J 38522 Variable Signal Generator
Circuit/System Verification
1. Ignition ON, observe the DTC information with a scan tool. Verify DTC P0121 and P0221 are not set.
• If either DTC is set, refer to DTC P0121, P0122, P0123, P0221, P0222, or P0223 (P0121).
2. Engine idling for 1 minute, observe the DTC information with a scan tool. DTC P0101 should not set.
3. 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. Ignition OFF, open the hood to disable the Auto-Stop function.
2. Ignition ON, verify the scan tool hood position parameter displays Open.
• If the hood position does not display Open, refer to DTC P254F (P254F).
3. Inspect for the following conditions:
* An engine vacuum leak
* An air leak in the intake air duct between the mass air flow (MAF) sensor and the throttle body
* A plugged or collapsed intake air duct
* Objects that block the MAF sensor air inlet
* An air filter element that is restricted
* The hydro-carbon absorber in the air cleaner assembly for ruptures or deterioration.
* A restricted throttle plate or for carbon build-up around the throttle plate
* An unseated engine oil dip stick
* A loose or missing engine oil fill cap
* An over filled crankcase
• If you find any of the above conditions, repair as necessary.
4. Ignition OFF, remove the fuse that supplies B+ to circuit terminal X2-56 of the ECM.
5. Disconnect the harness connector at the MAF/IAT sensor.
6. 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.
7. Install the fuse that supplies B+ to circuit terminal X2-56 of the ECM.
8. Ignition ON, test for greater 9 V between the ignition voltage circuit terminal B and ground.
• If less than the specified range, test the ignition voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
9. 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 an open/high resistance or a short to ground. If the circuit/connections test normal, replace the ECM.
• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.
10. 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+, and ground the black lead.
11. Set the J 38522 Signal switch to 5 V, the Frequency switch to 5K, and the Duty Cycle switch to Normal.
12. Engine Idling, observe the scan tool MAF Sensor frequency parameter. The parameter should be between 4,950-5,025 Hz.
• If not within the specified range, test the signal circuit for a high resistance. If the circuit/connections test normal, replace the ECM.
13. If all circuits/connections test normal, replace the MAF 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 engine control module replacement, setup, and programming