Buick Regal: DTC P0243, P0245, or P0246

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 Descriptors

DTC P0243

Turbocharger Wastegate Solenoid Valve Control Circuit

DTC P0245

Turbocharger Wastegate Solenoid Valve Control Circuit Low Voltage

DTC P0246

Turbocharger Wastegate Solenoid Valve Control Circuit High Voltage

Diagnostic Fault Information

Circuit/System Description

The dual-scroll turbocharger incorporates a wastegate that is controlled by the engine control module (ECM) by means of a pulse width modulation (PWM) solenoid, to regulate the pressure ratio of the compressor. An ECM controlled compressor bypass valve is integrated into the unit to prevent compressor surging and damage from vibrations by opening during abrupt closed throttle conditions.

The bypass valve is open during closed throttle deceleration conditions to allow air to recirculate in the turbocharger and maintain compressor speed.

As engine load and RPM increase, the turbocharger bypass valve is commanded closed by the ECM. As soon as the throttle closes, the valve is commanded open to allow the turbocharger air to recirculate to prevent compressor surging.

Conditions for Running the DTCs

• Ignition is On or the engine is running.
• Battery voltage is between 11 - 32 V.
• The DTCs run continuously when the above conditions are met.

Conditions for Setting the DTCs

P0243

The ECM detects an open circuit on the turbocharger wastegate solenoid control circuit for greater than 2 s.

P0245

The ECM detects a short to ground on the turbocharger wastegate solenoid control circuit for greater than 2 s.

P0246

The ECM detects a short to voltage on the turbocharger wastegate solenoid control circuit for greater than 2 s.

Action Taken When the DTCs Set

• DTCs P0243, P0245, and P0246 are Type B DTCs.
• The ECM will disable boost control and limit the system to mechanical boost only, resulting in a substantial decrease in engine power.

Conditions for Clearing the MIL/DTCs

DTCs P0243, P0245, and P0246 are Type B DTCs.

Reference Information

Schematic Reference

Engine Controls Wiring Schematics (LTG)

Connector End View Reference

Component Connector End View Index

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

Control Module References for scan tool information

Circuit/System Verification

1. Ignition On 2. Verify a series of clicks, which increase in frequency, are heard or felt from the Q42 Turbocharger Wastegate Solenoid Valve when commanding the Turbocharger Wastegate Solenoid Valve between 15 - 100 % with a scan tool.

• If a series of clicks in increasing frequency are not heard or felt

Refer to Circuit/System Testing.

• Go to next step: If a series of clicks in increasing frequency is heard or felt

3. Verify the parameters listed below do not display Malfunction when commanding the Turbocharger Wastegate Solenoid Valve between 15 - 100 % with a scan tool.

• Turbocharger Wastegate Solenoid Valve Control Circuit High Voltage Test Status
• Turbocharger Wastegate Solenoid Valve Control Circuit Open Test Status
• Turbocharger Wastegate Solenoid Valve Control Circuit Low Voltage Test Status
• If Malfunction is displayed

Refer to Circuit/System Testing.

• Go to next step: If Malfunction is not displayed

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.

5. Verify a DTC does not set.

• If a DTC sets

Refer to Circuit/System Testing

• Go to next step: If a DTC does not set

6. All OK.

Circuit/System Testing

1. Ignition Off, disconnect the harness connector at the Q42 Turbocharger Wastegate Solenoid Valve, ignition On.

2. Verify a test lamp illuminates between the ignition circuit terminal 1 and ground.

• If the test lamp does not illuminate and the circuit fuse is good

1. Ignition Off.
2. Test for less than 2 Ω in the ignition circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.

• If the test lamp does not illuminate and the circuit fuse is open

1. Ignition Off, remove the test lamp.

NOTE: A short circuit in any component supplied by the fuse may cause the fuse to open and set a DTC when the component is activated.

2. Test for infinite resistance between the ignition circuit and ground.
   • If less than infinite resistance, repair the short to ground on the circuit.
   • If infinite resistance, test all components supplied by the fuse and replace as necessary.

• Go to next step: If the test lamp illuminates

3. Verify that a test lamp does not illuminate between the control circuit terminal 2 and the ignition circuit terminal 1.

• If the test lamp illuminates

1. Ignition Off, disconnect the harness connector at the K20 Engine Control Module.
2. Test for infinite resistance between the control circuit and ground.
   • If less than infinite resistance, repair the short to ground on the circuit.
   • If infinite resistance, replace the K20 Engine Control Module.

• Go to next step: If the test lamp does not illuminate

4. Remove the test lamp.

5. Verify the scan tool Turbocharger Wastegate Solenoid Valve Control Circuit High Voltage Test Status parameter is OK when commanding the Turbocharger Wastegate Solenoid Valve between 15 - 100 % with a scan tool.

• If OK is not displayed

1. Ignition Off, disconnect the harness connector at the K20 Engine Control Module, ignition On.
2. Test for less than 1 V between the control circuit and ground.
   • If 1 V or greater, repair the short to voltage on the circuit.
   • If less than 1 V, replace the K20 Engine Control Module.

• Go to next step: If OK is displayed

6. Install a 3 A fused jumper wire between the control circuit terminal 2 and the ignition circuit terminal 1.

7. Verify the scan tool Turbocharger Wastegate Solenoid Valve Control Circuit High Voltage Test Status parameter is Malfunction.

• If Malfunction is not displayed

1. Ignition Off, disconnect the harness connector at the K20 Engine Control Module.
2. Test for less than 2 Ω in the control circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the K20 Engine Control Module.

• Go to next step: If Malfunction is displayed

8. Test or replace the Q42 Turbocharger Wastegate Solenoid Valve.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Turbocharger Wastegate Regulator Solenoid Valve Replacement
• Control Module References for ECM replacement, programming and setup

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