Buick Regal: DTC P0236

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 Descriptor

DTC P0236

Turbocharger Boost Sensor Performance

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 (34.8 psi). The pressure is equal to the BARO when the engine is idling or decelerating.

Conditions for Running the DTC

• DTC P0106, P0107, P0108, P0237, P0238, P2227, P2228, P2229, or P2230 is not set.
• DTC P0106, P0107, P0108, P0237, or P0238 is not pending.
• Ignition is ON.
• Engine is OFF.
• 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 P0102, P0103, P0107, P0108, P0111, P0112, P0113, P0114, P0116, P0117, P0118, P0128, P0237, P0238, P0335, P0336, P2227, P2228, P2229 or P2230 is not set.
• DTC P0112, P0113, P0117, or P0118 is not pending.
• Engine speed is between 400 - 6, 000 RPM.
• Engine Coolant Temperature (ECT) is between -7 to +125ºC (19.4 - 257ºF).
• Intake Air Temperature (IAT) is between -20 to +125ºC (-4 to +257ºF).
• The DTC runs continuously when the above conditions have been met.

Conditions for Setting the DTC

• The ECM detects that the boost pressure sensor signal is not within range of a model derived from engine speed, the BARO sensor, the MAF sensor, the MAP sensor, the throttle position sensor and the turbocharger boost pressure sensor when the engine is running.

  OR

• The ECM detects that the boost pressure sensor signal is less than 50 kPa (7.3 psi) or greater than 115 kPa (16.7 psi) when the ignition is ON and the engine is NOT rotating.

  OR

• The ECM detects that the difference between MAP and BARO is less than or equal to 10 kPa and the difference between turbocharger boost pressure and MAP is greater than 10 kPa and the difference between turbocharger boost pressure and BARO is greater than 10 kPa when the ignition is ON and the engine is NOT rotating.

Action Taken When the DTC Sets

DTC P0236 is a Type B DTC.

Conditions for Clearing the MIL/DTC

DTC P0236 is a Type B DTC.

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 Wiring Schematics (LTG)

Connector End View Reference

Component Connector End View Index

Description and Operation

Turbocharger System Description

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

1. Verify that DTC P0641, P0651, P0697, P06A3, or P06D2 is not set.

• If a DTC is set

Refer to Diagnostic Trouble Code (DTC) List - Vehicle.

• Go to next step: If none of the DTCs are set

2. If you were sent here from DTC P0068, P0101, P0106, P0121, or P1101 refer to Circuit/System Testing.

3. Ignition ON.

4. Verify the scan tool Throttle Body Idle Airflow Compensation parameter is less than 90%.

• If 90% or greater

Refer to Throttle Body Cleaning.

• Go to next step: If less than 90%

5. Verify the scan tool Throttle Position Sensors 1 and 2 Agree/Disagree parameter displays Agree while performing the Throttle Sweep Test with a scan tool.

• If Disagree

Refer to DTC P0121-P0123, P0222, P0223, P16A0-P16A2, or P2135.

• Go to next step: If Agree

6. Verify the scan tool BARO parameter is within the range specified in the Altitude Versus Barometric Pressure table, for the current vehicle testing altitude.

• BARO is not in range

Refer to DTC P2227-P2230.

• Go to next step: BARO is within range

7. Verify the scan tool MAP Sensor pressure and BARO parameters are within 3 kPa (0.4 psi).

• The parameters are not within 3 kPa (0.4 psi).

Refer to DTC P0106.

• Go to next step: The parameters are within 3 kPa (0.4 psi).

8. Engine idling.

9. Verify the scan tool MAP Sensor pressure parameter is between 26 - 52 kPa (3.8 - 7.5 psi) and changes with accelerator pedal input.

• If not between 26 - 52 kPa (3.8 - 7.5 psi) or does not change

Refer to DTC P0106.

• Go to next step: If between 26 - 52 kPa (3.8 - 7.5 psi) and changes

10. Verify the scan tool MAF Sensor g/s parameter changes smoothly and gradually as the engine speed is increased and decreased while performing the actions listed below.

1. Engine idling
2. Perform the scan tool snapshot function.
3. Increase the engine speed slowly to 3, 000 RPM and then back to idle.
4. Exit from the scan tool snapshot and review the data.
5. Observe the MAF Sensor parameter frame by frame with a scan tool.

• The MAF Sensor parameter does not change smoothly and gradually

Refer to DTC P0101.

• Go to next step: The MAF Sensor parameter changes smoothly and gradually

12. Verify the scan tool MAP Sensor parameter and the Boost Pressure Sensor parameter are within 20 kPa (2.9 psi) during a WOT acceleration at the time of the 1-2 shift.

• The parameters are not within 20 kPa (2.9 psi)

Refer to Circuit/System Testing.

• Go to next step: The parameters are within 20 kPa (2.9 psi)

13. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

14. Verify a DTC does not set.

• If the DTC sets

Refer to Circuit/System Testing.

• Go to next step: If the DTC does not set

15. All OK.

Circuit/System Testing

1. Verify that DTC P0237 or P0238 is not set.

• If a DTC is set

Refer to DTC P0237 or P0238.

• Go to next step: If none of the DTCs are set

2. Verify the conditions listed below do not exist:

• Loose clamps, cracks, or other damage in the air intake duct system
• Collapsed or restricted air intake duct system
• Restricted air filter
• Splits, kinks or improper connections at the vacuum hoses
• Missing, restricted or leaking exhaust components - Refer to Symptoms - Engine Exhaust.
• Vacuum leaks at the intake manifold and throttle body
• If a condition exists

Repair as necessary.

• Go to next step: If none of the conditions exist

3. Replace the B111B turbocharger boost/intake air temperature sensor.

Repair Instructions

• Perform the Diagnostic Repair Verification after completing the repair.

  Intake Air Pressure and Temperature Sensor Replacement for turbocharger boost/intake air temperature sensor replacement.

• Control Module References for engine control module replacement, programming, and setup

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