Service Information

Cruze

DTC P0236, P0237, or P0238

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0236 00: Turbocharger Boost Sensor Performance

DTC P0237 00: Turbocharger Boost Sensor Circuit Low Voltage

DTC P0238 00: Turbocharger Boost Sensor Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
5V Reference	P0642	P0237 00	P0643	P0236 00, P0234 00, P0299 00
Signal Circuit	P0237 00	P0237 00, P0238 00	P0238 00	P0236 00, P0234 00, P0299 00
Low Reference	-	P0098 00, P0234 00, P0238 00, P0237 00	-	-

Typical Scan Tool Data

Turbocharger Inlet Pressure Sensor Circuit

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Engine Running Parameter Normal Range: BARO to 240 kPa (34.80 PSI)
5V Reference	20-80 kPa (2.9 - 11.60 PSI)	30-80 kPa (4.35-11.60 PSI)	20-80 kPa (2.9 - 11.60 PSI)
Signal Circuit	0 kPa	276 kPa (40 PSI)	276 kPa (40 PSI)
Low Reference	-	276 kPa (40 PSI)	-

The boost pressure sensor is integrated with the inlet 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, inlet 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

•	Inlet 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 inlet 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

•	The ignition is ON or the engine is running.

•	These DTCs runs continuously within the enabling conditions.

Conditions for Setting the DTC

P0237 00

The ECM detects that the boost pressure sensor voltage is less than 0.19 V for more than 4 s continuously, or 50 s cumulative.

P0238 00

The ECM detects that the boost pressure sensor voltage is greater than 4.8 V for more than 4 s continuously, or 50 s cumulative.

Action Taken When the DTC Sets

•	DTCs P0237 00 and P0238 00 are Type C 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 P0237 00 and P0238 00 are Type C 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 ductwork 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

Connector End View Reference

Component Connector End Views

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, observe the scan tool Boost Pressure Sensor parameter, and the BARO Sensor parameter. Compare the parameters to each other.
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.
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

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 Q41 Turbocharger Vane Position Control Solenoid Valve

•	Any hairline fractures of the B111 Turbocharger Boost Sensor

•	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 Q41 Turbocharger Vane Position Control Solenoid Valve

•	Any restrictions in the vacuum hoses attached to the Q41 Turbocharger Vane Position Control Solenoid Valve

•	Improper routing or connecting of the vacuum hoses on the charge air cooler and the Q41 Turbocharger Vane Position Control 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.

Ignition OFF, disconnect the harness connector at the B111 Turbocharger Boost Sensor.
Ignition OFF for 90 s, test for less than 5 Ω between the low reference circuit terminal 2 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.

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.

Verify the scan tool Boost Pressure Sensor parameter is at 5 V.

⇒	If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module.

⇒	If greater than the specified range, test the signal circuit terminal 1 for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module.

Install a 3 A fused jumper wire between the signal circuit terminal 1 and ground. Verify the scan tool Turbocharger Pressure Sensor is less than 0.3 V.

⇒	If greater than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

If all circuits/connections test normal, replace the B111 Turbocharger Boost Sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Turbocharger Pressure Sensor Replacement

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