P0234
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
Diagnostic Fault Information
Typical Scan Tool Data
Circuit Description
The intake air pressure sensor is integrated with the intake air temperature (IAT) sensor 2. The intake air 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, 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 BARO. When the vehicle is operated at wide-open throttle (WOT) the turbocharger can increase the pressure to near 240 kPa. The least pressure that occurs is when the vehicle is idling or decelerating, and it is equal to the BARO.
Conditions for Running the DTCs
* DTC P0010, P0011, P0013, P0014, P0016, P0017, P0018, P0033, P0034, P0035, P00C0, P0101, P0102, P0103, P0106, P0107, P0108, P0111, P0112, P0113, P0114, P0121, P0122, P0123, P0128, P0222, P0223, P0234, P0236, P0237, P0238, P0243, P0245, P0246, P0299, P0606, P16F3, P2101, P2227, P2228, P2229, P2230 or P2261 is not set.
* The driver requested boost pressure level exceeds the level of the base boost pressure.
* The engine speed is between 1600-6000 RPM.
* The desired boost pressure is between 140-300 kPa.
* The Barometric Pressure (BARO) is between 60-120 kPa.
* The Engine Coolant Temperature (ECT) is between -40-120°C (-40-248°F).
* The Intake Air Temperature (IAT) is between -40-80°C (-40-176°F)
* The turbocharger wastegate is not under output device control.
* The turbocharger bypass valve is not under output device control.
* The DTCs run continuously when the above conditions have been met.
Conditions for Setting the DTC
P0234
The ECM detects that the actual boost pressure is greater than the desired boost pressure by a calibrated amount for greater than 1.5 s.
P0299
The ECM detects that the actual boost pressure is less than the desired boost pressure by a calibrated amount for greater than 1.5 s.
Action Taken When the DTC Sets
* DTCs P0234 and P0299 are Type B DTCs.
* An indicator will illuminate.
* 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/DTC
DTCs P0234 and P0299 are Type B DTCs.
Diagnostic Aids
* The charge 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 ductwork, the tightening specifications and proper positioning of the clamps is critical, and must be strictly adhered to.
* Use a solution of dish soap and water in a spray bottle to pinpoint any air leaks.
Reference Information
Schematic Reference
Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Connector End Views By Name
Description and Operation
Turbocharger System Description Description and Operation
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 Programming and Relearning for scan tool information
Circuit/System Verification
1. Ignition ON, command the Turbocharger Bypass Solenoid ON and OFF with a scan tool. A click should be heard and felt in response to the commands.
2. Command the Turbocharger Wastegate Solenoid between 20-90 % with a scan tool. A series of clicks should be heard and felt in response to the commands.
3. Ignition ON, observe the scan tool MAP Sensor, Boost Pressure Sensor and BARO Sensor parameters. Compare the parameters to the Altitude Versus Barometric Pressure Altitude Versus Barometric Pressure table. The parameters should be within the range specified in the table for the current altitude.
4. Compare the scan tool MAP Sensor parameter to the Boost Pressure Sensor parameter during a WOT acceleration at the time of the 1-2 shift. The readings should be within 20 kPa.
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 systems, including all turbocharger components, by inspecting for the following conditions:
* Damaged components
* Hairline fractures of the boost pressure sensor housing
* Hairline fractures of the MAP sensor housing
* Loose or improper installation
* An air flow restriction
* Vacuum line restrictions
* Vacuum leaks
* An air leak between the turbocharger and the throttle body, including the charge air cooler assembly.
* Verify that an exhaust leak does not exist, including the mating surface area between the turbocharger and the exhaust manifold.
* Verify that restrictions do not exist in the exhaust system. Refer to Restricted Exhaust Restricted Exhaust
• If a condition is found, repair or replace the affected component as necessary.
2. If all inspections are normal, test or replace the B65 intake air pressure and temperature sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Intake Air Pressure and Temperature Sensor Replacement Intake Air Pressure and Temperature Sensor Replacement
* Control Module References Programming and Relearning for ECM replacement, setup, and programming