DTC P0234: Turbocharger/Supercharger "A" OVERBOOST Condition: Notes

DTC detecting condition: 

Detected when two consecutive driving cycles with fault occur.

Trouble symptom:  Poor driving performance

1. CHECK DTC. 
   1. Turn the ignition switch to ON.
   2. Using the Subaru Select Monitor or a general scan tool, read the DTC of [Engine]. Ref. to COMMON (DIAG)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Are DTCs P0234 and P0244 displayed? (Current malfunction)

   Yes:  Go to  2.

   No:  Check the appropriate DTC using the "Diagnostic Trouble Code (DTC)". Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST .

2. CHECK ADAPTABILITY OF ELECTRONIC WASTEGATE VALVE ACTUATOR (AT IDLING). 
   1. Turn the A/C switch to OFF.
   2. Turn all the accessory switches to OFF.
   3. Using the Subaru Select Monitor, select [Electric Waste Gate Valve Control] of [Active Test].
      NOTE:

      • For detailed operation procedures, refer to the "Active Test". Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>ACTIVE TEST .
      • Electronic wastegate valve actuator repeats open and closed every 3 seconds with [Electric Waste Gate Valve Control] selected.
   4. Record the values of [Electric Waste Gate Valve Request Position Value] and [Electric Waste Gate Valve Actual Position Value].

      Is the difference between [Electric Waste Gate Valve Request Position Value] and [Electric Waste Gate Valve Actual Position Value] (except immediately after the change) 6.4 mm (0.25 in) or less?

      Yes:  Go to  3.

      No:  Replace the turbocharger. Ref. to INTAKE (INDUCTION) (H4DOTC)>TURBOCHARGER .

3. CHECK ADAPTABILITY OF ELECTRONIC WASTEGATE VALVE ACTUATOR (AT DRIVING). 
   1. Start monitoring of [Electric Waste Gate Valve Request Position Value] and [Electric Waste Gate Valve Actual Position Value] using Subaru Select Monitor.
      NOTE: For detailed operation procedures, refer to "Common (Diagnostics)". Ref. to COMMON (DIAG)>DATA MONITOR .
   2. Perform the corresponding inspection mode. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>INSPECTION MODE .
      WARNING:

      • Performing inspection mode needs a driver along with a checker who should check the data. 
      • When performing inspection mode on a public road, pay sufficient attention to the traffic condition and give the highest priority to safe driving. 
   3. Record the values of [Electric Waste Gate Valve Request Position Value] and [Electric Waste Gate Valve Actual Position Value].

   Is the difference between [Electric Waste Gate Valve Request Position Value] and [Electric Waste Gate Valve Actual Position Value] (except immediately after the change) 6.4 mm (0.25 in) or less?

   Yes:  Go to  4.

   No:  Replace the turbocharger. Ref. to INTAKE (INDUCTION) (H4DOTC)>TURBOCHARGER .

4. CHECK INTAKE AIR SYSTEM PARTS. 

   Check the following items.

   • Intercooler Ref. to INTAKE (INDUCTION) (H4DOTC)>INTERCOOLER>INSPECTION .
   • Intake duct Ref. to INTAKE (INDUCTION) (H4DOTC)>INTAKE DUCT>INSPECTION .
   • Intake manifold Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>INTAKE MANIFOLD ASSEMBLY>INSPECTION .
   • Air cleaner element Ref. to INTAKE (INDUCTION) (H4DOTC)>AIR CLEANER ELEMENT>INSPECTION .
   • Throttle body Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>THROTTLE BODY>INSPECTION>OTHER INSPECTIONS .
   • Turbo duct Ref. to INTAKE (INDUCTION) (H4DOTC)>TURBOCHARGER>INSPECTION .

   Is the check result OK?

   Yes:  Replace the manifold absolute pressure and intake air temperature sensor. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>MANIFOLD ABSOLUTE PRESSURE AND INTAKE AIR TEMPERATURE SENSOR>REMOVAL .

   No:  Repair or replace faulty parts.