P0236

CIRCUIT DESCRIPTION
The powertrain control module (PCM) controls boost using the turbocharger wastegate solenoid. The solenoid is pulse width modulated (PWM). When the wastegate solenoid is not energized, the vacuum to the turbocharger wastegate solenoid is vented to atmosphere through the solenoid. As the pulse width is increased by the PCM, more vacuum is applied through the solenoid to the wastegate actuator. At idle a higher vacuum to the wastegate actuator helps keep the wastegate closed. At higher engine speeds the vacuum supplied by the solenoid is less, allowing the turbocharger boost pressure to overcome the wastegate actuator.

CONDITIONS FOR RUNNING THE DTC
The engine speed is more than 2,400 RPM for test 1.
or
The engine speed is more than 1,800 RPM but less than 2,400 RPM for test 2.

CONDITIONS FOR SETTING THE DTC
^ The boost pressure is greater than, less than, or equal to 20 kPa from a desired value that is internal to the PCM for test 1.
^ The conditions were met for 10 seconds.
or
^ The boost pressure is greater than, less than, or equal to 20 kPa from a desired value that is internal to PCM for test 2.
^ The conditions were met 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.

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
A vacuum leak or a pinched vacuum line may cause a DTC P0236. Check all of the vacuum lines and the components that are connected to the hoses for any leaks or sharp bends. Check the vacuum source. Also check for proper vacuum line routing.

The turbocharger actuator uses a pulse width modulated vacuum solenoid that causes the vacuum to fluctuate during normal conditions. A steady vacuum reading indicates a restricted solenoid vent filter or a solenoid vent orifice.

TEST DESCRIPTION

Steps 1-9:

Steps 10-17:

The numbers below refer to the step numbers on the diagnostic table.
3. This will check the wastegate solenoid and the filter. A plugged filter will not allow the solenoid to vent, which will cause an overboost condition.
5. This step checks the turbocharger wastegate actuator for vacuum leaks. The actuator must hold a vacuum.
6. This step will check for vacuum leaks at the lines.
9. This step will check for a skewed boost pressure sensor.