Federal RPO FE9, NG1

DTC P0234 (FEDERAL WITH RPO CODE FE9, NG1)

CIRCUIT DESCRIPTION
The boost 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 sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The ECM supplies 5 volts to the boost sensor on a 5-volt reference circuit, and provides a ground on a low reference circuit. The boost sensor provides a voltage signal to the ECM on a signal circuit relative to the pressure changes. The ECM monitors the boost 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 above the predicted range.

CONDITIONS FOR RUNNING THE DTC
- DTC P0238 is not set.
- The engine speed is less than 2,700 RPM.
- The fuel quantity is less than 70 mm(3).
- The total fuel quantity burned is more than 2,000 mm(3).

CONDITIONS FOR SETTING THE DTC
The measured boost pressure is above the expected range by 35 kPa or more for 12 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.
- The ECM limits fuel delivery.

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.

DIAGNOSTIC AIDS
- Any changes to the induction system or exhaust system, such as the installation of aftermarket parts, may cause this DTC to set.
- If the condition is intermittent, refer to Intermittent Conditions. Diagnostic Strategies

TEST DESCRIPTION

Steps 1-5:

Steps 6-8:

Steps 9-15:

The numbers below refer to the step numbers on the diagnostic table.
5. This step tests the wastegate actuator diaphragm for a leak.
6. This step tests the wastegate actuator, the linkage, and the wastegate for proper operation.