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 P0234: Turbocharger Engine Overboost
DTC P0299: Turbocharger Engine Underboost

### Circuit/System Description

The turbocharger pressure sensor responds to pressure changes in the intake manifold. The pressure changes occur based on the engine load, and turbocharger boost. The engine control module (ECM) supplies 5 volts to the turbocharger pressure sensor on the 5-volt reference circuit. The ECM provides a ground on the low reference circuit. The turbocharger pressure sensor provides a signal to the ECM on the signal circuit which is relative to the pressure changes in the manifold.

### Condition for Running the DTC

• | The engine is operating.

• | The DTCs run continuously when the above conditions are met.

### Conditions for Setting the DTC

#### P0234

The actual turbocharger boost pressure is greater than the desired range for greater than 6 seconds.

#### P0299

The actual turbocharger boost pressure is less than the desired range for greater than 6 seconds.

### Action Taken When the DTC Sets

DTCs P0234 and P0299 are Type B DTCs.

### Conditions for Clearing the DTC

DTCs P0234 and P0299 are Type B DTCs.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

• | Engine Control Module Connector End Views

• | Engine Controls Connector End Views

#### Description and Operation

Turbocharger 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

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls

#### Special Tools

J 24460-01 Cooling System Pressure Tester

### Circuit/System Verification

1. Ignition ON, compare the scan tool boost pressure sensor parameter to the manifold absolute pressure (MAP) sensor parameter. Both parameters should be within 5 kPa.

⇒ | If the readings are not within the specified range, refer to DTC P0069 for further diagnosis.

2. Observe the DTC information with a scan tool. Verify that DTCs P0045, P0047, or P0048 are not set.

⇒ | If any of the DTCs are set, refer to DTC P0045, P0047, or P0048 for further diagnosis.

3. Engine idling, increase the engine speed to 2,000 RPM. Command the turbocharger boost solenoid from 0-100 percent and back to 0 percent with a scan tool. Verify the scan tool boost pressure sensor parameter increases and decreases with the scan tool commands.
4. 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

1. Inspect the intake, and the exhaust systems, for the following:

• | Leaks or restrictions

• | Damaged or missing components

• | Aftermarket components

⇒ | If a condition is found, repair as necessary.

2. Ignition OFF, remove the turbocharger boost pressure sensor from the intake manifold.
3. Connect the J 24460-01 to the turbocharger boost pressure port with a suitable adapter. Engine idling, observe the scan tool boost pressure parameter. Apply 6 psi to the boost pressure sensor. Verify the scan tool boost pressure sensor parameter responds to the applied pressure.

⇒ | If the scan tool boost pressure sensor parameter does not increase with the applied pressure, replace the turbocharger boost sensor.

4. Inspect the turbocharger oil supply lines for a restriction.

⇒ | If the turbocharger oil supply lines are restricted, repair or replace as necessary.

5. If all other components test OK, replace the turbocharger.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Turbocharger Pressure Sensor Replacement

• | Turbocharger Replacement

• | Control Module References for ECM replacement, setup, and programming