The actual throttle position and airflow rate is compared to an expected throttle position and airflow rate based on engine load. The engine control module (ECM) determines engine load based on inputs from the mass air flow (MAF) sensor and the manifold absolute pressure (MAP) sensor. Further comparisons are done to distinguish if a sensor is at fault, and the respective DTC will set.

The ECM uses the following information to calculate an expected airflow rate:

P0068

P0121

The ECM detects that the airflow rate is greater than the calculated airflow for greater than 0.2 second.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

Description and Operation Reference

Throttle Actuator Control (TAC) System Description

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Verify that DTCs P0101, P0106, P0120, P012B, or P0220 are not set.

⇒	If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle.

2. Ignition ON, observe the scan tool BARO, MAP, and the SC Inlet Pressure sensor parameters. The readings should be within the range specified for your altitude. Determine the altitude at your current location and refer to Altitude Versus Barometric Pressure.
3. Start the engine. The Manifold Absolute Pressure (MAP) and SC Inlet Pressure Sensor parameters should decrease and closely match each other.

⇒	If the MAP sensor parameter does not decrease, refer to DTC P0106.

⇒	If the SC Inlet Pressure Sensor parameter does not decrease, refer to DTC P012B.

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.

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

1. Inspect for the following conditions:

•	Vacuum hoses for splits, leaks, and improper connections

•	Air leaks at throttle body mounting area and intake manifold sealing surfaces

•	A supercharger bypass valve that is binding or incorrectly adjusted--Refer to Supercharger Cleaning and Inspection.

•	Inspect throttle body for dirt, debris, and coking. Refer to Throttle Body Inspection and Cleaning.

⇒	If any of the above conditions are found, repair as necessary.

2. Allow the engine to reach operating temperature. Observe the MAP Sensor Voltage parameter with a scan tool. Voltage should be greater than 0.8 volt and less than 4 volts.

⇒	If greater than 4 volts or less than 0.8 volt, refer to DTC P0106.

3. Idle the engine. Observe the MAP Sensor kPa parameter with a scan tool. Increase the engine speed slowly and then back to idle. The MAP sensor kPa should change smoothly and gradually as engine speed is increased and returned to idle.

⇒	If the MAP sensor kPa does not change, refer to DTC P0106.

4. Take a snapshot of the engine data list while performing the actions listed below. The mass airflow (MAF) sensor g/s should change smoothly and gradually as the engine is increased and returned to idle.

4.1.	Idle the engine.

4.2.	Increase the engine speed slowly to 3,000 RPM, then back to idle.

4.3.	Exit from the snapshot and review the data.

4.4.	Observe the Mass Air Flow (MAF) Sensor parameter frame by frame with a scan tool. The MAF sensor g/s should change smoothly and gradually as the engine speed is increased and is returned to idle.

⇒	If the MAF sensor g/s does not change smoothly and gradually as the engine speed is increased and is returned to idle, refer to DTC P0101 or P1101.

5. Ignition ON, slowly depress the accelerator pedal to a WOT position, then slowly release the pedal while comparing the TP Sensor 1 and TP Sensor 2 parameters. The difference between the parameters should be less than 4 percent.

⇒	If TP Sensor 1 and TP Sensor 2 parameters differ more than 4 percent, refer to DTC P0120, P0122, P0123, P0220, P0222, P0223, or P2135.

Warning: Turn OFF the ignition before inserting fingers into the throttle bore. Unexpected movement of the throttle blade could cause personal injury.

6. Ignition OFF, inspect the throttle body for the following conditions:

•	Loose or damaged throttle blade

•	Broken throttle shaft

•	Any throttle body damage

⇒	If any of these conditions exist, replace the throttle body assembly.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.