For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### 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 engine is running.

• | 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

#### Description and Operation

Throttle Actuator Control (TAC) System Description

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### 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.

1. 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.

2. Engine running, observe the MAP Sensor parameter. The reading should be between 32-42 kPa.
3. 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.

### Circuit/System Testing

1. Verify 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

• | Missing, restricted, or leaking exhaust components--Refer to Symptoms - Engine Exhaust.

• | Vacuum leaks at the intake manifold, throttle body, and injector O-rings

2. 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.

• | Throttle Body Assembly Replacement

• | Air Cleaner Inlet Duct Replacement

• | Air Cleaner Element Replacement