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 diagnosis of the barometric pressure (BARO) sensor and to provide engine overboost protection. The boost pressure sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The engine control module (ECM) supplies 5 volts to the boost pressure sensor on the 5-volt reference 2 circuit, and provides a ground on a low reference circuit. The boost pressure 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 pressure sensor. The ECM then compares the predicted value to the actual signal. This diagnostic trouble code (DTC) will set if the boost pressure sensor signal is below the predicted range.
Conditions for Running the DTC
| • | DTC P0237 is not set. |
| • | The engine is running. |
| • | 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 for 30 seconds.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | 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 emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Test Description
The number below refesr to the step number on the diagnostic table.
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||
2 |
Is the BARO sensor pressure more than the BOOST sensor pressure by a margin of the specified value or more? | 8 kPa | Go to Step 9 | Go to Step 3 | ||||||||
3 |
Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 4 | ||||||||
4 |
Does the scan tool indicate the boost pressure 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 pressure sensor pressure returns to the value observed in Step 2? | -- | Go to Step 6 | Go to Step 14 | ||||||||
6 | Inspect for the following conditions:
Did you find and correct the condition? | -- | Go to Step 16 | 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? | -- | Go to Step 8 | Go to Step 13 | |||||||||
8 |
Did you find a problem with the turbocharger? | -- | Go to Step 13 | Go to Intermittent Conditions | ||||||||
9 |
Does the scan tool indicate that the pressure is more than the specified value? | 254 kPa | Go to Step 11 | Go to Step 10 | ||||||||
10 | Test the signal circuit of the boost sensor for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 12 | ||||||||
11 | 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 16 | Go to Step 14 | ||||||||
12 | 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 16 | Go to Step 15 | ||||||||
13 | Replace the turbocharger. Refer to Turbocharger Replacement in Engine Mechanical. Did you complete the replacement? | -- | Go to Step 16 | -- | ||||||||
14 | Replace the boost pressure sensor. Refer to Boost Sensor Replacement . Did you complete the replacement? | -- | Go to Step 16 | -- | ||||||||
15 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 16 | -- | ||||||||
16 |
Does the DTC run and pass? | -- | Go to Step 17 | Go to Step 2 | ||||||||
17 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||||||
