Important: The following applies to the intake airflow system performance diagnostic that is used in this supercharged engine:

The intake airflow system performance diagnostic provides the within-range rationality check for the mass air flow (MAF), supercharger inlet absolute pressure (SCIAP), MAP, by-pass valve stuck, and the throttle position (TP) sensors. This is an explicit model-based diagnostic containing 4 separate models for the intake system.

The estimates of MAF, SCIAP, and TP that are obtained from this system of models and calculations are then compared to the actual measured values from the MAF, SCIAP, 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.

The engine control module (ECM) detects that the actual measured airflow from the MAF, MAP, SC Inlet Pressure, and the TP sensors are not within a range of the calculated airflow that are derived from the system of models by greater than a calibrated threshold for greater than 10 seconds.

DTCs P0101 and P1101 are Type B DTCs.

DTCs P0101 and P1101 are Type B DTCs.

Inspect for the following conditions that may set this DTC:

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Special Tools

J 38522 Variable Signal Generator

1. Verify that the following DTCs are not set: P0641 or P0651.

⇒	If any of the DTCs are set, refer to DTC P0641 or P0651

2. Verify restrictions do not exist in the exhaust system--Refer to Restricted Exhaust.
3. Ignition ON, observe the MAP Sensor and SC Inlet Pressure Sensor kPa parameters with a scan tool. Start the engine and let it idle. The MAP and SC Inlet Pressure Sensor kPa parameters should decrease and closely match each other.

⇒	If the MAP Sensor kPa parameter does not decrease and closely match each other, refer to DTC P0106.

⇒	If the SC Inlet Pressure kPa parameter does not decrease and closely match each other, refer to DTC P012B.

4. Ignition ON, depress the accelerator pedal completely to wide open throttle (WOT) and observe the TP Indicated Angle parameter with a scan tool. The TP Indicated Angle parameter should read 98-100 percent.

⇒	If the TP Indicated Angle parameter is not within the specified range, refer to DTC P1516, P2101, P2119, or P2176.

5. Ignition ON, engine OFF, perform a snapshot of the throttle actuator control (TAC) data while performing the following actions. Refer to Scan Tool Snapshot Procedure.

5.1.	Slowly depress the accelerator pedal to WOT position and then slowly release the pedal. Exit from the snapshot and review the data.

5.2.	Compare the TP Sensor 1 Indicated Position and the TP Sensor 2 Indicated Position parameters, frame by frame. The difference between the values should be less than 4 percent.

⇒	If the difference is greater than 4 percent, refer to DTC P0120, P0122, P0123, P0220, P0222, P0223, or P2135.

6. Road test the vehicle and perform a brief wide open throttle (WOT) acceleration from 30 mph. The MAP sensor parameter on the scan tool should increase rapidly. This increase should be from approximately 35 kPa at idle to greater than 135 kPa.

⇒	If the MAP Sensor parameter does not increase to greater than the specified range, refer to Boost Control System Diagnosis.

7. Road test the vehicle and verify that the MAF sensor calculated g/s and the actual MAF g/s parameters are near or equal to each other.
8. A skewed or stuck ECT, BARO, MAP, MAF/IAT, or IAT sensor 2 will cause the calculated models to be inaccurate and may cause this DTC to run when it should not. Refer to Temperature Versus Resistanceand Altitude Versus Barometric Pressure.
9. 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.

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

1. Visually and physically inspect the by-pass valve and cable for any of the following conditions:

•	A binding or sticking when opening or closing

•	An incorrectly adjusted cable

⇒	If any of the above conditions are found, refer to Supercharger Cleaning and Inspection.

2. Verify the integrity of the entire supercharger air induction system by inspecting for the following conditions:

•	A restricted or collapsed air intake duct

•	A misaligned or damaged air intake duct

•	A dirty or deteriorating air filter element

•	Any objects blocking the air inlet probe of the MAF/IAT sensor

•	Any contamination or debris on the sensing elements in the probe of the MAF/IAT sensor

•	Any water intrusion in the induction system

•	Any unmetered air downstream of the MAF/IAT sensor

•	An intake manifold leak

•	Any snow or ice build up at the air cleaner or MAF/IAT sensor

•	A SCIAP sensor vacuum hose that is missing or damaged

•	A MAP sensor vacuum hose that is missing or damaged

3. Ignition OFF and scan tool disconnected, disconnect the harness connector at the MAF sensor.
4. Ignition OFF for 90 seconds, test for less than 5 ohms between the ground circuit terminal B and ground.

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

5. Ignition ON, test for 4.8-5.2 volts between the MAF sensor signal circuit terminal A and ground.

⇒	If less than the specified range, test the MAF sensor 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 MAF sensor signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.

6. Ignition ON, verify that a test lamp illuminates between the MAF sensor ignition 1 voltage circuit terminal C and ground.

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

7. Ignition OFF, connect the read lead of 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.
8. Set the J 38522 signal to 5 volts, the Frequency to 5K, and the Duty Cycle to Normal.
9. Engine idling, observe the scan tool MAF Sensor parameter. The scan tool MAF Sensor parameter should be between 4,950-5,025 Hz.

⇒	If the MAF Sensor parameter is not within the specified range, replace the ECM.

10. If all circuits test normal, test or replace the MAF Sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.