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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/System Description

The boost pressure sensor is integrated with the intake air temperature (IAT) 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 boost pressure sensor and integrated intake air temperature (IAT) sensor have the following circuits:

* 5 V reference

* Low reference

* Intake air pressure signal

* IAT sensor signal

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 BARO. When the vehicle is operated at wide open throttle (WOT) the turbocharger can increase the pressure to near 240 kPa (34.80 PSI). The least pressure that occurs is when the vehicle is idling or decelerating, and it is equal to the BARO.

Conditions for Running the DTC

P0236

* Engine speed between 400-6 000 RPM.

* Engine coolant temperature between -7-125°C (19.4-257°F).

* Intake air temperature between -20-100°C (-4-212°F).

* DTCs P0016, P0017, P0096, P0097, P0098, P00B6, P0101, P0102, P0103, P0106, P0107, P0108, P0111, P0112, P0113, P0114, P0116, P0117, P0118, P0119, P0234, P0236, P0237, P0238, P0299, P0315, P0335 or P0336 are not set.

P0237, P0238

* The engine is running.

* These DTCs run continuously within the enabling conditions.

Conditions for Setting the DTC

P0236

The ECM determines if the turbocharger boost pressure sensor input is stuck within the normal operating range.

P0237

The ECM detects a continuous short to low or open in either the signal circuit or the turbocharger boost pressure sensor. The ECM detects that the boost pressure sensor voltage is less than 1 V.

P0238

The ECM detects an open sensor ground or continuous short to high in either the signal circuit or the turbocharger boost pressure sensor. The ECM detects that the boost pressure sensor voltage is greater than 4.8 V.

Action Taken When the DTC Sets

* DTCs P0236, P0237 and 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.

* The service vehicle soon indicator will illuminate.

Conditions for Clearing the DTC

DTCs P0236, P0237 and P0238 are Type B DTCs.

Diagnostic Aids

* The boost pressure sensor signal circuit is pulled high in the ECM. With the sensor disconnected, at ignition ON, a normal voltage measurement of the signal circuit with a DMM is 5.60 V.

* 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.

* Use a solution of dish soap and water in a spray bottle to pinpoint any air leaks.

* The BARO sensor is integrated within the ECM, and it has a port on the housing that allows it to sense the ambient pressure. Any restriction at this opening may hinder the operation of the BARO sensor.

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

* Turbocharger System Description (LUJ) Turbocharger System Description (LUJ)

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 scan tool Manifold Absolute Pressure (MAP) Sensor parameter, the Boost Pressure Sensor parameter, and the BARO Sensor parameter.

2. Engine idling, observe the scan tool and compare the Boost Pressure Sensor parameter to the BARO Sensor parameter. They should be within 4 kPa (0.58 PSI) of each other.

3. Use the scan tool and compare the 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 (2.9 PSI) of each other.

4. 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 system including all turbocharger components by inspecting for the following conditions:

* Any damaged components, including the turbocharger, the charge air cooler, and the Q42 Turbocharger Wastegate Solenoid Valve

* Any hairline fractures of the B65 Intake Manifold Pressure and Air Temperature Sensor housing

* Loose or improper installation of any components

* An air flow restriction

* Any vacuum leak

* Any pinholes or breaks in the vacuum hoses attached to the Q42 Turbocharger Wastegate Solenoid Valve

* Any restrictions in the vacuum hoses attached to the Q42 Turbocharger Wastegate Solenoid Valve

* Improper routing or connecting of the vacuum hoses on the charge air cooler, the Q40 Turbocharger Bypass Solenoid Valve, and the Q42 Turbocharger Wastegate Solenoid Valve

* Any type of 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.

2. Ignition OFF, disconnect the harness connector at the B65 Intake Manifold Pressure and Air Temperature Sensor.

3. Ignition OFF for 90 s, test for less than 5 ohms between the low reference circuit terminal 1 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 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 turbocharger Inlet Pressure Sensor parameter is less than 1 kPa (0.14 PSI).

• If less than the specified range, test the signal circuit terminal 4 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 and the 5 V reference circuit terminal 3. Verify the scan tool turbocharger Inlet Pressure Sensor is greater than 250 kPa (36.26 PSI).

• If less 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 all circuits/connections test normal, replace the B65 Intake Manifold Pressure and Air Temperature Sensor.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Manifold Absolute Pressure Sensor Replacement Service and Repair

* Control Module References Control Module References for ECM replacement, programming and setup

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