Circuit Description
The boost pressure sensor responds to pressure changes in the intake manifold. This pressure is created by the turbocharger and changes with accelerator pedal position (APP) and engine speed. The engine control module (ECM) uses this information to assist in the diagnosis of the barometric pressure (BARO) sensor and to provide engine overboost protection. The boost sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. ECM supplies 5 volts to the boost sensor on the 5-volt reference 2 circuit, and provides a ground on a low reference circuit. The boost sensor provides a signal to the ECM on a signal circuit relative to the pressure changes. The ECM monitors the boost pressure sensor signal for voltage outside of the normal range. The ECM calculates a predicted value for the boost sensor. The ECM then compares the predicted value to the actual signal. This DTC will set if the boost sensor signal is below the predicted range.
Conditions for Running the DTC
| • | DTC P0237 is not set. |
| • | The engine speed is between 500-2,700 RPM. |
| • | The total fuel quantity burned is more than 2,000 mm³. |
| • | The coolant temperature is more than 72°C (158°F). |
Conditions for Setting the DTC
The actual boost pressure sensor signal is below the predicted range by 50 kPa for 12 seconds.
Action Taken When the DTC Sets
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | The driver information center, if equipped, may display a message. |
Conditions for Clearing the DTC
| • | A current DTC Last Test Failed clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Clear the DTC with a scan tool. |
Test Description
The number below refer to the step number on the diagnostic table.
-
With the ignition ON and the engine OFF, the BARO sensor and the boost sensor should indicate the current barometric pressure. A significant difference between the readings indicates an electrical fault.
-
The spring in the wastegate actuator should return the wastegate via the linkage back to the closed position.
Step | Action | Values | Yes | No | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | ||||||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||||||
Is the boost sensor pressure less than the BARO sensor pressure by more than the specified value? | 10 kPa | Go to Step 9 | Go to Step 3 | |||||||||||||
3 |
Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 4 | ||||||||||||
4 |
Does the scan tool indicate the boost sensor is operating normally? | -- | Go to Step 5 | Go to Step 9 | ||||||||||||
5 | Disconnect the hand vacuum pump from the sensor. Does the scan tool indicate that the boost sensor pressure returns to the value observed in step 2? | -- | Go to Step 6 | Go to Step 16 | ||||||||||||
6 | Inspect for the following conditions:
Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 7 | ||||||||||||
|
Caution: Wear safety glasses when using compressed air in order to prevent eye injury.
Does the wastegate move to the fully extended position and return to the fully retracted position? | -- | Go to Step 8 | Go to Step 15 | |||||||||||||
8 |
Did you find a problem with the turbocharger? | -- | Go to Step 15 | Go to Intermittent Conditions | ||||||||||||
9 |
Does the test lamp illuminate? | -- | Go to Step 10 | Go to Step 11 | ||||||||||||
10 | Connect a 3-amp fused jumper wire between the 5-volt reference circuit of the boost sensor and the signal circuit of the boost sensor. Does the scan tool indicate that the pressure is more than the specified value? | 254 kPa | Go to Step 13 | Go to Step 12 | ||||||||||||
11 | Test the 5-volt reference circuit of the boost sensor for high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the conditions? | -- | Go to Step 18 | Go to Step 14 | ||||||||||||
12 | Test the signal circuit of the boost sensor for an open or for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 14 | ||||||||||||
13 | Inspect for poor connections at the boost pressure sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 16 | ||||||||||||
14 | Inspect for poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 17 | ||||||||||||
15 | Replace the turbocharger. Refer to Turbocharger Replacement in Engine Mechanical. Did you complete the replacement? | -- | Go to Step 18 | -- | ||||||||||||
16 | Replace the boost sensor. Refer to Boost Sensor Replacement . Did you complete the replacement? | -- | Go to Step 18 | -- | ||||||||||||
17 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 18 | -- | ||||||||||||
18 |
Does the DTC run and pass? | -- | Go to Step 19 | Go to Step 2 | ||||||||||||
19 | Observe the stored information in Capture Info. with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||||||||||
