Diagnostic Instructions
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
Description and Operation
Turbocharger System Description
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Special Tools
J 24460-01
Cooling System Pressure Tester
Circuit/System Verification
- 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. |
- Observe the DTC information with a scan tool. Verify that DTCs P0045, P0047, or P0048 are not set.
- 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.
- 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
- Inspect the intake, and the exhaust systems, for the following:
• | Damaged or missing components |
⇒ | If a condition is found, repair as necessary. |
- Ignition OFF, remove the turbocharger boost pressure sensor from the intake manifold.
- 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. |
- Inspect the turbocharger oil supply lines for a restriction.
⇒ | If the turbocharger oil supply lines are restricted, repair or replace as necessary. |
- If all other components test OK, replace the turbocharger.
Repair Instructions
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.