P0299
DTC P0234 or P0299
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC P0234
- Engine Overboost
DTC P0299
- Engine Underboost
Circuit/System Description
The intake manifold pressure and air temperature sensor or the boost pressure sensor measures the range of pressure between the turbocharger and the throttle body. The sensor used on this engine is a three wire 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 intake manifold pressure and air temperature sensor has the following circuits:
* 5 V reference
* Low reference
* Intake air pressure signal
* IAT sensor signal
The intake manifold pressure and air temperature sensor or the boost pressure sensor provides a signal voltage to the engine control module (ECM), relative to the pressure changes, on the intake air pressure signal circuit. 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 barometric pressure (BARO). When the engine is operated at wide open throttle (WOT) the turbocharger can increase the pressure to near 210 kPa (30.50 PSI). The least pressure that occurs is when the engine is idling or decelerating.
Conditions for Running the DTC
P0234 or P0299
* 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).
* Desired Boost Pressure Derivative between -70-55 kPa/s (-10.2-8 kPa/s).
* Ambient pressure between 60-120 kPa (8.70-17.40 PSI).
* Coolant temperature between -40-120°C (-40-248°F)
* Intake air temperature between -40-80°C (-40-176°F)
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.
Reference Information
Schematic Reference
Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
Description and Operation
* Boost Control System Description (LUJ) Boost Solenoid, Turbocharger
* Boost Control System Description (LUJ) Boost Solenoid, Turbocharger
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON, observe the DTC information with a scan tool. Verify that DTC P0033, P0034, P0035, P0236, P0237, P0238, P0243, P0245, or P0246 is not set.
• If any of the DTCs are set, refer toDiagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.
2. Command the Turbocharger Bypass Solenoid Valve ON and OFF with a scan tool. A click should be heard and felt in response to the commands.
3. Command the Turbocharger Wastegate Solenoid Valve between 20-90% and then back to 0%. A click should be heard and felt in response to the commands.
4. Compare the Manifold Absolute Pressure (MAP) Sensor parameter to the Boost Pressure Sensor parameter during a WOT acceleration. The readings should be within 20 kPa (2.9 PSI) of each other.
5. 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
1. Verify the integrity of the entire air induction and exhaust system including all turbocharger components by inspecting for the conditions listed below:
* The air intake duct system for loose clamps, cracks or other damage
* The air intake duct system for being collapsed or restricted
* Restricted air filter
* An air flow restriction
* Any type of 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 vacuum 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
- Turbocharger bypass valve
* Missing, restricted or leaking exhaust components. Refer to Restricted Exhaust 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 as necessary.
2. Remove the hose from the turbocharger wastegate actuator.
3. Connect a hand vacuum pump to the actuator and apply 51 kPa (15 inches Hg) of vacuum. The vacuum pump should hold vacuum for 10 s
• If vacuum is not held for 10 s, replace the turbocharger
4. Using the pressure port on the vacuum pump, apply pressure to the wastegate actuator. The wastegate actuator rod should move open approximately 15 mm (1/2 inches).
• If the wastegate actuator rod does not move, replace the turbocharger.
5. Disconnect the turbocharger wastegate solenoid valve vacuum line from the turbocharger inlet pipe. Connect a vacuum pump to the vacuum line.
6. Apply 51 kPa (15 inches Hg) of vacuum to the turbocharger wastegate solenoid valve. Verify the pressure decreases to 0 kPa (0 inches Hg) when commanding the Turbocharger Wastegate Solenoid Valve ON with a scan tool.
• If not the specified value, replace the turbocharger wastegate solenoid valve.
7. Disconnect the vacuum hose at the turbocharger bypass valve.
8. Install a vacuum gauge to the hose of the turbocharger bypass valve.
9. Engine Idling, verify the vacuum gauge displays between 51-67 kPa (15-20 inches Hq) of vacuum.
• If not within the specified range, inspect and repair the leaking vacuum hose in the areas listed below:
* Between the turbocharger bypass valve and the turbocharger bypass solenoid valve
* Between the intake manifold and the turbocharger bypass solenoid valve
10. Disconnect the vacuum hose at the turbocharger vacuum reservoir on the bottom of intake manifold.
11. Connect a hand vacuum pump to the turbocharger vacuum reservoir and apply 34 kPa (10 inches Hg) of vacuum. The vacuum pump should hold vacuum for 10 s.
• If the vacuum does not hold, replace the intake manifold.
12. Engine idling, vacuum gauge still installed from step 8, command the bypass solenoid valve ON and OFF with the scan tool. Vacuum should toggle between 0 kPa (0 inches Hg) when OFF to greater than 51 kPa (15 inches Hg) when ON.
• If no change in vacuum, replace turbocharger bypass solenoid valve.
13. If all components test normal, replace the turbocharger.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Charge Air Bypass Regulator Solenoid Valve Replacement Charge Air Bypass Regulator Solenoid Valve Replacement
* Manifold Absolute Pressure Sensor Replacement Service and Repair
* Control Module References Control Module References for ECM replacement, programming and setup