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DTC P0236, P0237, or P0238

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

Turbocharger Boost System Performance

DTC P0237

Turbocharger Boost Sensor Circuit Low Voltage

DTC P0238

Turbocharger Boost Sensor Circuit High Voltage

Diagnostic Fault Information

Circuit Short to Ground High Resistance Open Short to Voltage Signal Performance
5 V Reference

P0642

P0236, P0237

P0237

P0236, P0643

P0234, P0236, P0299

Boost Pressure Sensor Signal

P0237

P0236, P0237

P0238

P0238

P0236

Low Reference

-

P0238

P0238

-

-



Typical Scan Tool Data

Intake Air Pressure and Temperature Sensor

Circuit Short to Ground Open Short to Voltage
Operating Conditions: Engine running at various operating conditions

Parameter Normal Range: BARO to 240 kPa (35 psi)

5 V Reference

20-80 kPa

(2.9-11.6 psi)

30-80 kPa

(4.4-11.6 psi)

20-80 kPa

(2.9-11.6 psi)

Intake Air Pressure Sensor Signal

0 kPa

276 kPa

(40 psi)

276 kPa

(40 psi)

Low Reference

-

276 kPa

(40 psi)

-



Circuit 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. Pressure in this portion of the induction system is affected by the following:


Engine speed

Throttle opening

Turbocharger boost pressure

Intake air temperature (IAT)

Barometric pressure (BARO)

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 boost pressure sensor signal circuit. During normal operation, the highest pressure that can occur in this part of the intake manifold with the ignition ON and the engine OFF is equal to the barometric pressure (BARO). When the vehicle is run with wide open throttle (WOT) , the turbocharger can increase the pressure to close to 240 kPa (35 psi). The least amount of pressure that occurs is when the vehicle is idling or decelerating, and it is equal to the BARO.

Conditions for Running the DTC


P0236

DTCs P0121, P0122, P0123, P0221, P0222, P0223, P0237, P0238, P2227, P2228, or P2229 are not set.

The engine is running.

The engine speed is less than 1,120 RPM.

The Throttle Position Sensor parameter is less than 10%.

This DTC runs continuously within the enabling conditions.



P0237

The engine is running.

This DTC runs continuously within the enabling conditions.



P0238

The engine is running.

This DTC runs continuously within the enabling conditions.


Conditions for Setting the DTC


P0236

The ECM detects that the boost pressure sensor signal plus a calibrated threshold is less than the BARO sensor signal plus a calibrated threshold.

OR

The ECM detects that the boost pressure sensor signal plus a calibrated threshold greater than the BARO sensor signal plus a calibrated threshold.


P0237

The ECM detects that the boost pressure sensor voltage is less than 0.45 V or the measured pressure is less than 50 kPa (7.3 psi).

P0238

The ECM detects that the boost pressure sensor voltage is greater than 4.65 V or the measured pressure is greater than 300 kPa (43.5 psi).

Action Taken When the DTC Sets

DTCs P0236, P0237, P0238 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0236, P0237, P0238 are Type B DTCs.

Diagnostic Aids


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

Connector End View Reference

Component Connector End Views

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. Ignition ON, observe the diagnostic trouble code (DTC) information with a scan tool. Verify that DTCs P0641, P0642, P0643, P2227, P2228, or P2229 are not set.

2. If any of the above DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.

3. Compare the scan tool BARO parameter to the Altitude Versus Barometric Pressure table. The BARO should be within the specified range displayed in the table for the specific altitude.

4. If not within the specified range, refer to DTC P2227, P2228, or P2229 (LAU) for further diagnosis.

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

Any damaged components

Intake air pressure and temperature sensor damage

A buildup of contamination, snow or ice at the BARO port on the ECM

Loose or improper installation

An air flow restriction

Any vacuum leak

Any type of air leak between the turbocharger and the throttle body

Exhaust leaks

2. If a condition is found, repair as necessary.

3. Ignition OFF, disconnect the harness connector at the B65 intake air pressure and temperature sensor.

4. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 5 Ω between the low reference circuit terminal 1 and ground.

5. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.

6. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 3 and ground.

7. 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 ECM.

8. 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 ECM.

9. Verify the scan tool Boost Pressure Sensor parameter is greater than 250 kPa (36.3 psi).

10. 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 ECM.

11. Install a 3 A fused jumper wire between the signal circuit terminal 4 and the low reference circuit terminal 1. Verify the scan tool Boost Pressure Sensor parameter is less than 1 kPa (0.15 psi).

12. 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 ECM.

13. If the circuits test normal, test or replace the B65 intake air pressure and temperature sensor.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


Turbocharger Pressure Sensor Replacement for intake air pressure and temperature sensor replacement

Control Module References for Engine Control Module replacement, setup, and programming