The mass air flow (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 voltage signal to provide the correct fuel delivery for a reduction in emissions. The ECM uses the MAF sensor signal to control fuel delivery until a calibrated amount of engine air flow is attained. The MAF sensor produces an output voltage based on the inlet air flow through the air induction system. This output voltage will display on the scan tool as a voltage parameter and as a grams per second (g/s) parameter. The ECM compares the actual MAF sensor voltage signal to a predicted MAF value. This comparison will determine if the signal is stuck, or is too low or too high for a given operating condition.

The ECM detects that the MAF sensor voltage signal is not within a predetermined range of the calculated MAF value for greater than 15 seconds.

DTC P0101 is a Type B DTC.

DTC P0101 is a Type B DTC.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

DTC Type Reference

Scan Tool Reference

Special Tools

J 46091 Charge Air Cooler Tester

1. If DTC P0102, P0103, or P0405 are set, diagnose these DTC first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle .
2. Verify the integrity of the entire air induction system by inspecting for the following conditions:

•	Restrictions in the MAF air induction system and the turbocharger system

•	Restrictions in the exhaust system--Refer to Restricted Exhaust .

•	Leaks at the MAF/IAT sensor O-ring seal

•	Cracked or damaged MAF sensor housing

•	Restricted intake air duct or a dirty air filter element

•	Debris blocking the air sensing filaments of the MAF sensor

•	Snow or ice build-up in cold climates at the air cleaner, MAF, or MAP sensor do not exist.

3. Engine running, observe the DTC information with a scan tool. DTC P0101 should not set.
4. 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.

Important: All electrical components and accessories must be turned OFF and allowed to power down.

You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF, disconnect the harness connector at the MAF/IAT sensor.
2. Ignition OFF and scan tool disconnected for 90 seconds, test for less than 5 ohms between the low reference circuit terminal 4 and ground.

⇒	If greater than 5 ohms, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, verify a test lamp illuminates between the ignition circuit terminal 3 and ground.

⇒	If test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.

4. Ignition ON, verify the scan tool MAF sensor parameter is less than 0 g/s.

⇒	If greater than 0 g/s, test the signal circuit terminal 5 for a short to voltage. If the circuit tests normal, replace the ECM.

5. Install a 3A fused jumper wire between the signal circuit terminal 5 and the IAT signal circuit terminal 2. Verify the scan tool MAF sensor parameter is greater than 500 g/s.

⇒	If less than 500 g/s, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

6. Test for air leaks at the manifold absolute pressure (MAP) sensor seal.

⇒	If a leaking sensor seal is verified, repair as necessary.

7. Test the charge air cooler system for leaks. Refer to Charge Air Cooler Diagnosis .

⇒	If a charge air cooler leak is found, repair as necessary.

8. Remove the Intake Manifold Tube. Refer to Intake Manifold Tube Replacement .
9. Visually inspect the EGR valve and verify the valve is in the closed position.

⇒	If the EGR valve is not in the closed position, replace the EGR valve.

⇒	If the EGR valve inspection is normal, replace the MAF/IAT sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.