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Home >> Subaru >> 2017 >> Forester 2.0XT Touring >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Control System (Diagnostics) (P0171 To P0685) (H4DOTC) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P04F0 EVAP System High Pressure Purge Line (CPC2) Performance >> Notes

DTC P04F0 EVAP System High Pressure Purge Line (CPC2) Performance: Notes

DTC detecting condition: 

Detected when two consecutive driving cycles with fault occur.

Trouble symptom: 

Improper idling

CAUTION: After servicing or replacing faulty parts, perform Clear Memory Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>Clear Memory Mode>OPERATION . and Inspection Mode Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>Inspection Mode>PROCEDURE .
  1. CHECK FOR ANY OTHER DTC ON DISPLAY. 

    Is any other DTC displayed?

  2. CHECK PIPING BETWEEN PURGE CONTROL VALVE 2 AND TURBOCHARGER. 

    Check the piping between the purge control valve 2 and the turbocharger.

    Is there dislocation of the piping between the purge control valve 2 and the turbocharger?

  3. CHECK PIPING BETWEEN PURGE CONTROL VALVE 2 AND TURBOCHARGER. 

    Check the piping between the purge control valve 2 and the turbocharger.

    Is there clogging in the piping between the purge control valve 2 and the turbocharger?

  4. CHECK PURGE CONTROL VALVE 2. 

    Check the purge control valve 2.

    Is there closed or open stuck state in the purge control valve 2?

  5. CHECK PURGE CONTROL VALVE 1. 

    Check the main body of the purge control valve 1.

    Is there any leakage in the main body of the purge control valve 1?

  6. CHECK EVAPORATIVE EMISSION CONTROL SYSTEM LINE. 
    1. Turn the ignition switch to OFF.
    2. Make sure that the delivery mode fuse is removed.

    Are there holes, cracks, clogging, or disconnection, misconnection of hoses or pipes in evaporative emission control system?

    • Yes: Repair or replace the hoses or pipes.
    • No: Go to 7. 
  7. CHECK VACUUM PUMP OPERATION OF LEAK CHECK VALVE ASSEMBLY. 

    Check the vacuum pump operation of the leak check valve assembly. Ref. to EMISSION CONTROL (AUX. EMISSION CONTROL DEVICES) (H4DOTC)>Leak Check Valve Assembly>INSPECTION .

    Does the vacuum pump operate?

  8. CHECK SWITCHING VALVE OPERATION OF LEAK CHECK VALVE ASSEMBLY. 

    Check the switching valve operation of the leak check valve assembly. Ref. to EMISSION CONTROL (AUX. EMISSION CONTROL DEVICES) (H4DOTC)>Leak Check Valve Assembly>INSPECTION .

    Does the switching valve operate?