GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2005 🢒 TopKick C-Series (Conventional) C6/C7/C8 🢒 Restraints 🢒 SIR 🢒 DTC P0237

Circuit Description

The boost pressure sensor is located in the intake manifold. The boost pressure sensor is a transducer that varies voltage according to changes in the air pressure inside the intake manifold. The boost pressure sensor has the following circuits:

    • A 5-volt reference circuit
    • A low reference circuit
    • A boost pressure sensor signal circuit

The engine control module (ECM) supplies 5 volts to the boost pressure sensor on the 5-volt reference circuit. The ECM also provides a ground on the low reference circuit. The boost pressure sensor provides a signal to the ECM on the boost pressure signal circuit which is relative to the pressure changes in the manifold. The ECM should detect a low signal voltage at a low boost pressure, such as low engine load. The ECM should detect a high signal voltage at a high boost pressure, such as high engine load. The ECM monitors the boost pressure sensor signal for voltage outside the normal range of the boost pressure sensor. If the ECM detects an excessively low boost pressure sensor signal voltage, this DTC will set.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0237 Turbocharger Boost Sensor Circuit Low Voltage

Conditions for Running the DTC
    • The battery voltage is between 10-16 volts.
    • The ignition switch is ON.

Conditions for Setting the DTC

The ECM detects that the boost pressure sensor signal voltage is less than 0.1 volt.

Action Taken When the DTC Sets
    • The ECM illuminates the malfunction indicator lamp (MIL) and reduced engine power indicator lamp, if fitted, when the diagnostic runs and fails.
    • The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records.
    • The ECM uses a boost pressure substitution of 100 kPa (14.5 psi) when the DTC is set.
    • The ECM limits the fuel injection quantity for fail-safe operation.
    • The ECM limits the fuel rail pressure for fail-safe operation.

Conditions for Clearing the DTC
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • Clear the MIL and the DTC with a scan tool.

Step

Action

Values

Yes

No

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Install a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Monitor the Diagnostic Trouble Code (DTC) Information with a scan tool.

Is DTC P0641 also set?

--

Go to DTC P0641

Go to Step 3

3
  1. Start the engine.
  2. Observe the Boost Pressure Sensor parameter with a scan tool.

Is the Boost Pressure Sensor parameter less than the specified value?

34 kPa (5 psi)

Go to Step 4

Go to Intermittent Conditions

4
  1. Turn OFF the ignition.
  2. Disconnect the boost pressure sensor harness connector.
  3. Connect a test lamp between the 5-volt reference circuit of the boost pressure sensor harness and a known good ground.
  4. Connect a DMM to the probe at the test lamp and a known good ground. Refer to Measuring Voltage Drop and Circuit Testing .

Is the DMM voltage more than the specified value?

4.5 V

Go to Step 5

Go to Step 6

5
  1. Turn OFF the ignition.
  2. Connect a 3-amp fused jumper wire between the 5-volt reference circuit and the signal circuit of the boost pressure sensor harness.
  3. Turn ON the ignition, with the engine OFF.
  4. Observe the Boost Pressure Sensor parameter with a scan tool.

Is the Boost Pressure Sensor parameter more than the specified value?

254 kPa (36 psi)

Go to Step 8

Go to Step 7

6
  1. Test the 5-volt reference circuit between the engine control module (ECM) harness and the boost pressure sensor for the following conditions:
    2. • An open circuit
    • High resistance
  2. Repair the circuits as necessary.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 9

7
  1. Test the signal circuit between the ECM and the boost pressure for the following conditions:
    2. • An open circuit
    • A short to ground
    • A short to the low reference circuit
    • High resistance
  2. Repair the circuits as necessary.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 9

8
  1. Turn OFF the ignition.
  2. Inspect for an intermittent and for poor connections at the harness connector of the boost pressure sensor.
  3. Repair the circuits as necessary.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 10

9
  1. Turn OFF the ignition.
  2. Disconnect the ECM harness connector.
  3. Inspect for an intermittent and for a poor connection on the boost pressure sensor circuits at the harness connector of the ECM.
  4. Repair the connections as necessary.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 11

10

Replace the boost pressure sensor.

Did you complete the replacement?

--

Go to Step 12

--

11

Important: The replacement ECM must be programmed.

Replace the ECM. Refer to Engine Control Module Replacement/Restore Fuel Rate Data and Fuel Injector Flow Rate Programming .

Did you complete the replacement?

--

Go to Step 12

--

12
  1. Reconnect all previously disconnected harness connectors.
  2. Clear the DTCs with a scan tool.
  3. Turn OFF the ignition for 30 seconds.
  4. Start the engine.
  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 Failure Records.

Did the DTC fail this ignition?

--

Go to Step 3

Go to Step 13

13

Observe the stored information, Capture Info with a scan tool.

Are there any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle

System OK