Buick Regal: DTC 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 P0237
Turbocharger Boost Sensor Circuit Low Voltage
DTC P0238
Turbocharger Boost Sensor Circuit High Voltage
Diagnostic Fault Information
Typical Scan Tool Data
Boost Pressure Sensor
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
- Ignition is ON or the engine is running.
- The DTCs run continuously when the above conditions have been met.
Conditions for Setting the DTC
P0237
The ECM detects that the boost pressure sensor voltage is less than 0.9 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 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.
Conditions for Clearing the MIL/DTC
DTCs P0237 and P0238 are Type B DTCs.
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.
Refer to Diagnostic Trouble Code (DTC) List - Vehicle.
- Go to next step: If none of the DTCs are set
2. Verify the scan tool BARO parameter is within the range specified in the
Altitude Versus
Barometric Pressure table, for the current vehicle testing altitude.
Refer to DTC P2227-P2230.
- Go to next step: BARO is within range
3. Verify the scan tool Boost Pressure Sensor pressure and BARO parameters
are within 3 kPa (0.4
psi).
- The parameters are not within 3 kPa (0.4 psi).
Refer to Circuit/System Testing
- Go to next step: The parameters are within 3 kPa (0.4 psi).
4. 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)
5. 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.
6. Verify a DTC does not set.
Refer to Circuit/System Testing.
- Go to next step: If the DTC does not set
7. All OK.
Circuit/System Testing
1. Ignition OFF, and all vehicle systems OFF, disconnect the harness
connector at the B111B
turbocharger boost/intake air temperature sensor. It may take up to 2 minutes
for all vehicle
systems to power down.
2. Test for less than 5 Ω between the low reference circuit terminal 1 and
ground.
- Ignition OFF, disconnect the X1 harness connector at the K20 engine
control module.
- Test for less than 2 Ω in the low reference circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K20 engine control module.
- Go to next step: If less than 5 Ω
3. Ignition ON.
4. Test for 4.8 - 5.2 V between the 5 V reference circuit terminal 3 and ground.
- Ignition OFF, disconnect the X1 harness connector at the K20 engine
control module.
- Test for infinite resistance between the 5 V reference circuit and
ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- Go to next step: If infinite resistance
- Test for less than 2 Ω in the 5 V reference circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K20 engine control module
NOTE: If the signal circuit is shorted to a voltage the engine control
module or the sensor may be damaged.
- Ignition OFF, disconnect the X1 harness connector at the K20 engine
control module,
ignition ON.
- Test for less than 1 V between the 5 V reference circuit and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, replace the K20 engine control module.
- Go to next step: If between 4.8 - 5.2 V
5. Verify the scan tool Boost Pressure Sensor voltage parameter is less than
0.2 V.
- Ignition OFF, disconnect the X1 harness connector at the K20 engine
control module,
ignition ON.
- Test for less than 1 V between the signal circuit terminal 4 and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, replace the K20 engine control module.
- Go to next step: If less than 0.2 V
6. Install a 3 A fused jumper wire between the signal circuit terminal 4 and
the 5 V reference circuit
terminal 3.
7. Verify the scan tool Boost Pressure Sensor voltage parameter is greater than
4.5 V.
- Ignition OFF, disconnect the X1 harness connector at the K20 engine
control module.
- Test for infinite resistance between the signal circuit terminal 4 and
ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- Go to next step: If infinite resistance
- Test for less than 2 Ω in the signal circuit end to end.
- If 2 Ω or greater, repair the open or high resistance in the
circuit.
- If less than 2 Ω, replace the K20 engine control module.
- Go to next step: If greater than 4.5 V
8. Test or 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 ECM replacement, programming, and setup
READ NEXT:
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.
Diag
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.
Diag
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.
Diag
SEE MORE:
Removal Procedure
1. Control Valve Body - Remove - Refer to Control Valve Body Replacement.
2.
Input Speed Sensor Bolt (1) - Remove.
3. Input Speed Sensor (2) - Remove.
Installation Procedure
1.
Input Speed Sensor (2) - Install.
CAUTION: Refer to Fastener Caution.
2. Input Speed Sensor Bolt (1) -
Control Module
K71 Transmission Control Module
The TCM (2) is mounted directly on top of the transmission (1). The selector
lever and transmission range sensor is
integrated in the control module. The TCM is mounted so that the selector lever
shaft goes through the control
module. The selector le