Subaru Legacy BN/BS (2015-2019) Service Manual: Dtc p0458 evap system (cpc) purge control valve "a" circuit low

Subaru Legacy BN/BS (2015-2019) Service Manual / Engine (diagnostics)(h6do) / Diagnostic procedure with diagnostic trouble code (dtc) / Dtc p0458 evap system (cpc) purge control valve "a" circuit low

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 Mode Clear Memory Mode > OPERATION, and Inspection Mode Inspection Mode > PROCEDURE.

WIRING DIAGRAM:

• Engine Electrical System ENGINE TYPE EZ (WITHOUT PUSH BUTTON START) Engine Electrical System > WIRING DIAGRAM

• Engine Electrical System ENGINE TYPE EZ (WITH PUSH BUTTON START) Engine Electrical System > WIRING DIAGRAM

STEP	CHECK	YES	NO
1.CHECK OUTPUT SIGNAL OF ECM. 1) Turn the ignition switch to ON. 2) Measure the voltage between ECM connector and chassis ground. Connector & terminal (E158) No. 51 (+) — Chassis ground (−):	Is the voltage 10 V or more-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0458 EVAP SYSTEM (CPC) PURGE CONTROL VALVE "A" CIRCUIT LOW	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0458 EVAP SYSTEM (CPC) PURGE CONTROL VALVE "A" CIRCUIT LOW
2.CHECK FOR POOR CONTACT. Check for poor contact of ECM connector.	Is there poor contact of ECM connector-	Repair the poor contact of ECM connector.	Even if DTC is detected, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again. NOTE: In this case, temporary open or short circuit of harness or temporary poor contact of connector may be the cause.
3.CHECK POWER SUPPLY TO PURGE CONTROL SOLENOID VALVE. Measure the voltage between purge control solenoid valve and engine ground. Connector & terminal (E4) No. 1 (+) — Engine ground (−):	Is the voltage 10 V or more-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0458 EVAP SYSTEM (CPC) PURGE CONTROL VALVE "A" CIRCUIT LOW	Repair the power supply circuit.
4.CHECK HARNESS BETWEEN ECM AND PURGE CONTROL SOLENOID VALVE CONNECTOR. 1) Turn the ignition switch to OFF. 2) Disconnect the connectors from ECM and purge control solenoid valve. 3) Measure the resistance between the purge control solenoid valve connector and engine ground. Connector & terminal (E4) No. 2 — Engine ground:	Is the resistance 1 M- or more-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0458 EVAP SYSTEM (CPC) PURGE CONTROL VALVE "A" CIRCUIT LOW	Repair the short circuit to ground in harness between ECM connector and purge control solenoid valve connector.
5.CHECK HARNESS BETWEEN ECM AND PURGE CONTROL SOLENOID VALVE CONNECTOR. Measure the resistance of harness between ECM connector and purge control solenoid valve. Connector & terminal (E158) No. 51 — (E4) No. 2:	Is the resistance less than 1 --	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0458 EVAP SYSTEM (CPC) PURGE CONTROL VALVE "A" CIRCUIT LOW	Repair the harness and connector. NOTE: In this case, repair the following item: • Open circuit in harness between ECM connector and purge control solenoid valve connector • Poor contact of coupling connector
6.CHECK PURGE CONTROL SOLENOID VALVE. 1) Remove the purge control solenoid valve. 2) Measure the resistance between purge control solenoid valve terminals. Terminals No. 1 — No. 2:	Is the resistance 10 — 100 --	Repair the poor contact of purge control solenoid valve connector.	Replace the purge control solenoid valve. Purge Control Solenoid Valve

1. OUTLINE OF DIAGNOSIS

Detect open or short circuit of the purge control solenoid valve.

Judge as NG when the ECM output level differs from the actual terminal level.

2. COMPONENT DESCRIPTION

(A)

To canister

(B)

To intake manifold

3. EXECUTION CONDITION

Secondary Parameters	Execution condition
Battery voltage	≥ 10.9 V
Purge control solenoid valve control duty	< 0.75 - 100%

4. GENERAL DRIVING CYCLE

Perform the diagnosis continuously after the enable conditions have been established.

5. DIAGNOSTIC METHOD

If the duration of time while the following conditions are met is longer than the time indicated, judge as NG.

Judgment Value

Malfunction Criteria	Threshold Value
Terminal output voltage	≤ Battery voltage - 0.34

Time Needed for Diagnosis: 2500 ms

Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.

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DTC DETECTING CONDITION:Detected when two consecutive driving cycles with fault occur.TROUBLE SYMPTOM:Improper idlingCAUTION:After servicing or replacing faulty parts, perform Clear Memory Mode Clear ...

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