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Home >> Subaru >> 2023 >> WRX Base, Standard Trans >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (Diagnostics) (2 Of 4) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P04F0: EVAP System High Pressure Purge Line (CPC2) Performance >> General Description >> Outline Of Diagnosis

Outline Of Diagnosis

When a negative pressure is generated in the ejector mechanism of the intake manifold or the intake duct No. 1, the purge control solenoid valve performs opening/closing operation.

As a result, pressure pulsation occurs in the CPC pressure sensor area.

If pressure pulsation does not occur and the monitoring value (integral of pressure fluctuation) has not reached the threshold value, ECM judges that it is malfunctioning.

The monitor of P04F1 is executed when the intake manifold is at negative pressure, and when the pressure rises and the ejector mechanism functions, the monitoring of P04F0 is executed.

High pressure side pressure system (P04F0)

G16390509Courtesy of SUBARU OF AMERICA, INC.
(A) Monitor
(B) Fail flag
(C) Intake manifold gauge pressure (kPa)
(D) Purge control valve commanded DUTY (%)
(E) Purge line pressure (kPa)
(F) Monitoring value (integration of pressure variation)
(1) Normal Condition
(2) Malfunction Condition
(3) Enable
(4) Disable
(5) Malfunction not detected
(9) Fail
(7) Threshold
(8) Pass
(6) Malfunction detected

Low pressure side pressure system (P04F1)

G16390510Courtesy of SUBARU OF AMERICA, INC.
(A) Monitor
(B) Fail flag
(C) Intake manifold gauge pressure (kPa)
(D) Purge control valve commanded DUTY (%)
(E) Purge line pressure (kPa)
(F) Monitoring value (integration of pressure variation)
(1) Normal Condition
(2) Malfunction Condition
(3) Enable
(4) Disable
(5) Malfunction not detected
(9) Fail
(7) Threshold
(8) Pass
(6) Malfunction detected