Diagnostic Instructions
DTC Descriptor
DTC P0068: Throttle Body Airflow Performance
Circuit/System Description
The engine control module (ECM) compares actual airflow based on throttle position (TP) and manifold absolute pressure (MAP) sensor to a calculated airflow.
Conditions for Running the DTC
| • | DTCs P0106, P0107, P0108, P0110, P0111, and P0112 are not set. |
| • | The DTC runs continuously when the above conditions are met. |
Conditions for Setting the DTC
The ECM detects that the actual airflow rate is greater than the calculated airflow.
Action Taken When the DTC Sets
| • | DTC P0068 is a Type A DTC. |
| • | The ECM commands the TAC system to operate in a Reduced Engine Power mode. |
| • | DTCs P2106 and P2110 will set. |
Conditions for Clearing the DTC
DTC P0068 is a Type A DTC.
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Description and Operation:
Throttle Actuator Control (TAC) System Description
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Circuit/System Verification
Important: In extreme cold weather conditions ice may form in the vacuum source to the MAP sensor and may set a DTC. Inspect the MAP sensor and the vacuum source for ice, moisture, or other restrictions.
- Ignition ON, observe the MAP sensor pressure parameter and compare the reading on the scan tool to the barometric pressure table. Refer to
Altitude Versus Barometric Pressure
.
| ⇒ | If the MAP sensor pressure is not within the range specified for your altitude, refer to
DTC P0107 or P0108
. |
- Start the engine, observe the MAP Sensor parameter. The reading should be between 32-42 kPa.
- If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.
Circuit/System Testing
- Verify that none of the following conditions exist:
| • | The air intake duct system for loose connecting clamps, cracks, or other damage |
| • | The air intake duct system for being collapsed or restricted possibly by a restricted air filter |
| • | A damaged throttle body blade or shaft |
| • | Splits, kinks, or improper connections at the vacuum hoses |
| • | Vacuum leaks at the intake manifold, throttle body, and injector O-rings |
- If all conditions test normal, test the engine for a mechanical condition. Refer to
Symptoms - Engine Mechanical
.
Repair Instructions
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
