P0237
DTC P0236, P0237, or P0238
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 P0236
- Turbocharger Boost Sensor Performance
DTC P0237
- Turbocharger Boost Sensor Circuit Low Voltage
DTC P0238
- Turbocharger Boost Sensor Circuit High Voltage
Diagnostic Fault Information
Typical Scan Tool Data
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. The pressure is equal to the BARO when the engine is idling or decelerating.
Conditions for Running the DTC
P0236
* DTC P0106, P0107, P0108, P0237, P0238, P2227, P2228, P2229, P2230 or P2610 is not set.
* Ignition is ON.
* The time between current ignition cycle and the last time the engine was running is greater than 10 s.
* The DTC runs continuously when the above conditions have been met.
OR
* DTC P0097, P0098, P0102, P0103, P0106, P0107, P0108, P0111, P0112, P0113, P0114, P0116, P0117, P0118, P0121, P0122, P0123, P0128, P0222, P0223, P0237, P0238, P0335, P0336, P2227, P2228, P2229 or P2230 is not set.
* Engine speed is between 400-6,000 RPM.
* Engine Coolant Temperature (ECT) is between -7 to +125°C (19.4-257°F).
* Intake Air Temperature (IAT) is between -20 to +125°C (-4 to +257°F).
* The DTC runs continuously when the above conditions have been met.
P0237 and P0238
* Ignition is ON or the engine is running.
* The DTCs run continuously when the above conditions have been met.
Conditions for Setting the DTC
P0236
* The ECM detects that the boost pressure sensor signal is not within range of a model derived from the BARO sensor, the MAP sensor, the throttle position sensor and the boost pressure sensor when the engine is running.
OR
* The ECM detects that the boost pressure sensor signal is less than 50 kPa or greater than 115 kPa when the ignition is ON and the engine is NOT rotating.
P0237
The ECM detects that the boost pressure sensor voltage is less than 0.09 V for greater than 5 s.
P0238
The ECM detects that the boost pressure sensor voltage is greater than 3.9 V for greater than 5 s.
Action Taken When the DTC Sets
* DTCs P0236, P0237, P0238 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 MIL/DTC
DTCs P0236, P0237, P0238 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 duct work, the tightening specifications and proper positioning of the clamps is critical, and must be strictly adhered to.
* Use a smoke generating device or a solution of dish soap and water in a spray bottle to pinpoint any suspected air leaks in the induction system and in the charge air cooler assembly.
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. Verify that DTC P0641, P0651, P0697, or P06A3 is not set.
• If a DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.
2. Ignition ON, observe the scan tool MAP Sensor, Boost Pressure Sensor and the 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.
3. Engine idling, observe the scan tool Boost Pressure Sensor and the BARO Sensor parameters. The parameters should be within 4 kPa.
4. Compare the scan tool MAP Sensor and Boost Pressure Sensor parameters 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. Ignition OFF, disconnect the harness connector at the B111B turbocharger boost/intake air temperature sensor.
3. Ignition OFF and all vehicle systems OFF. It may take up to 2 min for all vehicle systems to power down. Test for less than 5 ohms between the low reference circuit terminal 1 or A and ground.
• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
4. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 3 or C and ground.
• If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
• If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 engine control module.
5. Verify the scan tool Boost Pressure Sensor parameter is greater than 275 kPa.
• If less than the specified range, test the signal circuit terminal 4 or D for a short to ground. If the circuit tests normal, replace the K20 engine control module.
6. Install a 3 A fused jumper wire between the signal circuit terminal 4 or D and the low reference circuit terminal 1 or A. Verify the scan tool Boost Pressure Sensor parameter is less than 1 kPa.
• If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
7. If the circuits test normal, test or replace the B111B turbocharger boost/intake air temperature sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Intake Air Pressure and Temperature Sensor Replacement Intake Air Pressure and Temperature Sensor Replacement for turbocharger boost/intake air temperature sensor replacement.
* Control Module References Programming and Relearning for ECM replacement, programming, and setup