Chevrolet Trax: DTC P0234 OR P0299

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 P0234

Engine Overboost

DTC P0299

Engine Underboost

Circuit Description

The boost pressure sensor is integrated with the turbocharger boost/intake air temperature sensor. The boost pressure sensor measures the range of pressures between the turbocharger and the throttle body. The sensor used on this engine is a three atmosphere sensor. Pressure in this portion of the induction system is affected by engine speed, throttle opening, turbocharger boost pressure, Intake air temperature (IAT), barometric pressure (BARO), and the efficiency of the charge air cooler.

The sensor provides a signal voltage to the engine control module (ECM), relative to the pressure changes.

Under normal operation the greatest pressure that can exist in this portion of the induction system at ignition ON, engine OFF is equal to the BARO. When the engine is operated at wide-open throttle (WOT) the turbocharger can increase the pressure to near 240 kPa (34.8 psi). The pressure is equal to the BARO when the engine is idling or decelerating.

Conditions for Running the DTC

• DTCs P0010, P0011, P0013, P0014, P0033, P0034, P0035, P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0111, P0112, P0113, P0114, P0116, P0117, P0118, P0119, P0121, P0122, P0123, P0128, P0222, P0223, P0234, P0236, P0237, P0238, P0243, P0245, P0246, P0299, P16F3, P2101, P2227, P2228, P2229 or P2230 are not set.
• Engine speed between 2,450-6,000 RPM.
• Desired boost pressure between 135-220 kPa (19.58-31.90 PSI).
• Ambient pressure between 60-120 kPa (8.70-17.40 PSI).
• Coolant temperature between -40 to +120ºC (-40 to +248ºF)
• Intake air temperature between -40 to +80ºC (-40 to +176ºF)

Conditions for Setting the DTC

P0234

The ECM detects that the actual boost pressure is greater than the desired boost pressure for greater than 2 s.

P0299

The ECM detects that the actual boost pressure is less than the desired boost pressure for greater than 2.5 s.

Action Taken When the DTC Sets

• DTCs P0234 and P0299 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 DTC

DTCs P0234 and P0299 are Type B DTCs.

Diagnostic Aids

• The charged air cooler is connected to the turbocharger and to the throttle body by flexible duct work that requires the use of special high torque fastening clamps. These clamps cannot be substituted. In order to prevent any type of air leak when servicing the duct work, the tightening specifications and proper positioning of the clamps is critical, and must be strictly adhered to.
• An excessively worn wastegate pivot pin may allow the wastegate to open slightly when commanded closed, which may result in P0299 being set.

Reference Information

Schematic Reference

Engine Controls Schematics (Encore) , Engine Controls Schematics (Trax)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

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 (LUV) , Powertrain Diagnostic Trouble Code (DTC) Type Definitions (2H0)

Control Module References for scan tool information

Special Tools

GE-23738-A Vacuum Pump

For equivalent regional tools, refer to Special Tools (Diagnostic Tools) .

Circuit/System Verification

1. Ignition ON.
2. Verify DTC P0033, P0034, P0035, P0236, P0237, P0238, P0243, P0245, or P0246 is not set.

• If any of the DTCs are set

Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

• If none of the DTCs are set

3. Verify the scan tool BARO Sensor parameter is within the range specified in the Altitude Versus Barometric Pressure table for the current testing altitude.

• If the parameter is not within the range specified in

Refer to DTC P2227-P2230

• If the parameter is within the range specified in the table

4. Verify the scan tool MAP Sensor and BARO Sensor parameters are within 3 kPa (0.4 psi) .

• If the parameters are not within 3 kPa (0.4 psi).

Refer to DTC P0106.

• If the parameters are within 3 kPa (0.4 psi).

5. Verify the scan tool Boost Pressure Sensor and BARO Sensor parameters are within 3 kPa (0.4 psi) .

• If the parameters are not within 3 kPa (0.4 psi).

Refer to DTC P0236.

• If the parameters are within 3 kPa (0.4 psi).

6. Verify a click is heard or felt from the Q40 Turbocharger Bypass Solenoid Valve when commanding the Turbocharger Bypass Solenoid Valve between Active and Inactive with a scan tool.

• If a click is not heard or felt

Refer to Circuit/System Testing.

• If a click is heard or felt

7. 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.

• If a series of clicks in increasing frequency is heard or felt

8. Verify the scan tool MAP Sensor parameter and the Boost Pressure Sensor parameter are within 20 kPa (2.9 psi) during a WOT acceleration at the time of the 1-2 shift.

• If the parameters are not within 20 kPa (2.9 psi)

Refer to Circuit/System Testing.

• If the parameter are within 20 kPa (2.9 psi)

9. 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.
10. Verify a DTC does not set.

• If a DTC sets

Refer to Circuit/System Testing

• If a DTC does not set

11. All OK

Circuit/System Testing

1. Verify the conditions listed below do not exist:

• Loose clamps, cracks or other damage in the air intake duct system
• Collapsed or restricted intake duct system
• Restricted air filter
• Any air flow restriction
• Any air leak between the turbocharger and the throttle body, including the charge air cooler assembly
• Splits, kinks or improper connections at the vacuum hoses
• Any vacuum leak
• Restricted, leaking or incorrect routing of hoses going to the components listed below:

• Turbocharger wastegate solenoid valve
• Turbocharger bypass solenoid valve
• Intake manifold and turbocharger vacuum reservoir on the bottom of intake manifold
• Turbocharger
• Turbocharger wastegate actuator
• Turbocharger bypass valve

• Missing, restricted or leaking exhaust components. Refer to Restricted Exhaust
• Exhaust leak between the turbocharger and the exhaust manifold
• Restricted turbocharger oil supply line
• Loose or incorrect installation of any components

If a condition exists

Repair or replace the affected component as necessary.

If none of the conditions exist

NOTE:

The hose is attached between the turbocharger inlet and the Q42 Turbocharger Wastegate Solenoid Valve.

2. Ignition OFF, disconnect the turbocharger wastegate solenoid valve hose at the turbocharger and apply 51 kPa (15 inches Hg) of vacuum to the hose with the GE 23738-A . Ignition ON.
3. Verify the pressure decreases to 0 kPa (0 inches Hg) when commanding the Turbocharger Wastegate Solenoid Valve to 15 % with a scan tool.

• If the pressure does not decrease to 0 kPa (0 inches Hg)

Test or replace the Q42 Turbocharger Wastegate Solenoid Valve

• If the pressure decreases to 0 kPa (0 inches Hg)

4. Connect the turbocharger wastegate solenoid valve hose to the turbocharger.
5. Disconnect the wastegate solenoid valve hose from the turbocharger wastegate actuator and connect the exhaust/pressure port of the GE 23738-A , or a suitable hand pressure pump, to the actuator.
6. Verify the wastegate actuator rod moves when applying pressure to the actuator.

• If the actuator does not move

Replace the turbocharger

• If the actuator moves

7. Disconnect the Q40 Turbocharger Bypass Solenoid Valve vacuum supply hose at the intake manifold.
8. Connect the GE 23738-A to the manifold.

NOTE: Allow engine idle to stabilize before continuing.

9. Engine Idling, verify the vacuum gauge displays between 45-67 kPa (13-20 inches Hg) of vacuum.

• If not within the specified range

Repair the vacuum source.

• If within the specified range

NOTE: The vacuum reservoir (tank) is integral to intake manifold and is located at the bottom of the manifold.

10. Ignition OFF, disconnect the vacuum hose at the turbocharger vacuum reservoir.
11. Connect the GE 23738-A to the vacuum reservoir and apply 34 kPa (10 inches Hg) of vacuum.
12. Verify the reservoir holds vacuum for at least 10 s.

• If the vacuum is not held for at least 10 s

Replace the intake manifold

• If the vacuum is held for at least 10 s

13. Connect the vacuum hose to the reservoir.

NOTE: Disconnect the turbocharger bypass solenoid valve vacuum supply hose at the intake manifold if not still disconnected from step 7.

14. Disconnect the vacuum hose at the Q40 Turbocharger Bypass Solenoid Valve and connect the GE 23738- A to the hose.
15. Engine idling, command the Turbocharger Bypass Solenoid Valve ON and OFF with a scan tool.
16. Verify the vacuum toggles between 0 kPa (0 inches Hg) to greater than 45 kPa (13 inches Hg).

• If not within the specified range

Test or replace the Q40 Turbocharger Bypass Solenoid Valve

• If within the specified range

17. Connect any hoses that were disconnected during previous steps.
18. Verify the conditions listed below do not exist with the turbocharger assembly. Refer to Turbocharger Cleaning and Inspection

• Worn or damaged wastegate pivot pin
• Cracked, damaged or worn turbine blades
• Restricted wastegate, turbine, ports or passages
• Foreign material
• Damaged or restricted bypass valve assembly.
• If a condition exists

Repair or replace the turbocharger as necessary

• If none of the conditions exist

19. Replace the turbocharger.

Component Testing

Static Test

1. Ignition OFF, disconnect the harness connector at the appropriate solenoid Valve.
2. Test for 20-27 ohms between terminal 1 and terminal 2 of the solenoid valve.

• If not between 20-27 ohms

Replace the solenoid Valve.

• If between 20-27 ohms

3. All OK

Dynamic Test

1. Install a 10 A fused jumper wire between the Ignition terminal 2 and 12 V. Install a jumper wire between the control terminal 1 and ground.
2. Verify the solenoid clicks.

• If the solenoid does not click

Replace the solenoid Valve.

• If the solenoid clicks

3. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Charge Air Bypass Regulator Solenoid Valve Replacement
• Intake Manifold Replacement
• Turbocharger Replacement
• Turbocharger Wastegate Regulator Solenoid Valve Replacement
• Control Module References for ECM replacement, programming and setup

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