DTC P0234 or P0299
Diagnostic Instructions
DTC Descriptors
DTC P0234 00: Engine Overboost
DTC P0299 00: 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 V to the turbocharger pressure sensor on the 5 V 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.
Conditions for Running the DTC
• | The DTCs run continuously when the above conditions are met. |
Conditions for Setting the DTC
P0234 00
The actual turbocharger boost pressure is greater than the desired range for greater than 7 s.
P0299 00
The actual turbocharger boost pressure is less than the desired range for greater than 7 s.
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
Component Connector End Views
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Special Tools
EN 23738-A Mityvac
For equivalent regional tools, refer to Special Tools .
Circuit/System Verification
- Ignition ON, compare the scan tool Boost Pressure Sensor parameter to the Barometric Pressure (BARO) parameter. Both parameters should be within 5 kPa (0.72 PSI).
- Observe the DTC information with a scan tool. Verify that DTC P0047 or P0048 are not set.
- Engine running, increase the engine speed to 2 000 RPM. Command the Turbocharger Vane Position ON and OFF with a scan tool. Verify the scan tool Boost Pressure Sensor parameter increases and decreases with the scan tool commands.
- 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
- Inspect the fuel tank for the right fuel content.
- Inspect the intake, and the exhaust systems, for the following:
• | Damaged or missing components |
⇒ | If a condition is found, repair as necessary. |
- Disconnect the vacuum source from the Q41 Turbocharger Vane Position Control Solenoid Valve.
- Connect the EN 23738-A Mityvac to the Q41 Turbocharger Vane Position Control Solenoid Valve vacuum supply hose. Engine running, verify the vacuum is greater than -50 kPa (-7.25 PSI).
⇒ | If less than the specified range, inspect the vacuum supply hose and filter for a leak or restriction. If the supply hose is normal, replace the vacuum pump. |
- Connect the vacuum source to the Q41 Turbocharger Vane Position Control Solenoid Valve. Connect the EN 23738-A Mityvac to the Q41 Turbocharger Vane Position Control Solenoid Valve vacuum port on the Q41 Turbocharger Vane Position Control Solenoid Valve. Engine running, command the Turbocharger Vane Position to 5% with a scan tool. Verify the vacuum is between 0 to -40 kPa (0-5.8 PSI).
⇒ | If greater than the specified range, replace the Q41 Turbocharger Vane Position Control Solenoid Valve. |
- Command the Turbocharger Vane Position ON with a scan tool. Verify the vacuum is greater than -50 kPa (-7.25 PSI).
⇒ | If less than the specified range, replace the Q41 Turbocharger Vane Position Control Solenoid Valve. |
- Inspect the turbocharger oil supply lines for a restriction.
⇒ | If restricted, repair or replace as necessary. |
- If all other components test normal, replace the turbocharger.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
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