The mass air flow (MAF) sensor is integrated with the intake air temperature (IAT) sensor. The MAF sensor is an air flow meter that measures the amount of air entering the engine. The engine control module (ECM) uses the MAF sensor signal to provide the correct fuel delivery for all engine speeds and loads. A small quantity of air entering the engine indicates a deceleration or idle condition. A large quantity of air entering the engine indicates an acceleration or high load condition.

The ECM applies 5 volts to the MAF sensor on the MAF sensor signal circuit. The sensor uses the voltage to produce a frequency based on the inlet air flow through the sensor bore.

The ECM detects that the MAF sensor signal is not within a predetermined range of the calculated MAF value.

DTCs P0101 is a Type B DTCs.

DTCs P0101 is a Type B DTCs.

Inspect the harness of the MAF sensor to verify that it is not routed too close to the following components:

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Special Tools

EL 38522 Variable Signal Generator

1. Engine idling, observe the DTC information with a scan tool. DTC P0101 00 should not set.
2. Verify the scan tool MAF Sensor Hz parameter is between 1700 to 2100 Hz.
3. 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.

1. 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

•	Objects that block the MAF sensor air inlet

•	An air filter element that is restricted

•	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.

2. Ignition OFF, disconnect the harness connector at the B75B Mass Air Flow (MAF)/Intake Air Temperature (IAT) Sensor.
3. Ignition OFF for 90 s, test for less than 5 Ω between the ground circuit terminal 2 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

4. Ignition ON, load test for B+ between the ignition voltage circuit terminal 4 and ground.

⇒	If less than the specified range, test the ignition voltage circuit for a short to ground or an open/high resistance.

5. Ignition ON, test for 4.8 to 5.2 V between the signal circuit terminal 5 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 (ECM).

⇒	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 (ECM).

6. Ignition OFF, connect the red lead of the EL 38522 Variable Signal Generator to the signal circuit terminal 5 at the B75B Mass Air Flow (MAF)/Intake Air Temperature (IAT) Sensor harness connector. Connect the battery voltage supply to the B+, and ground the black lead.
7. Set the EL 38522 Variable Signal Generator to the following specifications signal switch to 5 V, the Frequency switch to 5 K, and the duty cycle switch to normal.

•	Signal switch to 5 V

•	Frequency switch to 5 Ω

•	Duty Cycle switch to Normal

Note: The engine will run rough and may stall.

8. Engine idling, observe the scan tool MAF Sensor Hz parameter. The scan tool MAF Sensor parameter should be between 4950 to 5025 Hz.

⇒	If the MAF Sensor parameter is not within the specified range, replace the K20 Engine Control Module (ECM).

9. If all other circuits test normal, test or replace the B75B Mass Air Flow (MAF)/Intake Air Temperature (IAT) Sensor.

Perform the Diagnostic Repair Verification after completing the repair.