Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSSUBARU2005OUTBACK I, STANDARDREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS - ENGINE (DIAGNOSTICS) (H4SO)DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)DTC P0447 EVAPORATIVE EMISSION CONTROL SYSTEM VENT CONTROL CIRCUIT OPEN

2005 Subaru Outback i, Standard

DTC P0447 Evaporative Emission Control System Vent Control Circuit Open

2005 Subaru Outback i, StandardSECTION DTC P0447 Evaporative Emission Control System Vent Control Circuit Open

DTC DETECTING CONDITION:

Two consecutive driving cycles with fault
GENERAL DESCRIPTION < Ref. to DTC P0447 EVAPORATIVE EMISSION CONTROL SYSTEM VENT CONTROL CIRCUIT OPEN , Diagnostic Trouble Code (DTC) Detecting Criteria. >

CAUTION: After repair or replacement of faulty parts, conduct CLEAR MEMORY MODE < Ref. to , OPERATION , Clear Memory Mode.> and INSPECTION MODE < Ref. to , PROCEDURE , Inspection Mode.>.

WIRING DIAGRAM:

Fig 1: DTC P0447 Evaporative Emission Control System Vent Control Circuit Open

Courtesy of SUBARU OF AMERICA, INC.

DTC P0447 EVAPORATIVE EMISSION CONTROL SYSTEM VENT CONTROL CIRCUIT OPEN DIAGNOSIS

Step	Check	Yes	No
1. CHECK OUTPUT SIGNAL FROM ECM. Turn ignition switch to ON. Measure the voltage between ECM and chassis ground. Connector & terminal (B134) No. 13 (+) - Chassis ground (-):	Is the voltage more than 10 V?	Go to step 2.	Go to step 3.
2. CHECK FOR POOR CONTACT. Check for poor contact in ECM connector.	Is there poor contact in ECM connector?	Repair poor contact in ECM connector.	The malfunction indicator light may light up, however, the circuit is returned to the normal status at the moment. (However, the possibility of poor contact still remains.) NOTE: In this case, repair the following: Poor contact in drain valve connector Poor contact in ECM connector Poor contact in coupling connector
3. CHECK HARNESS BETWEEN DRAIN VALVE AND ECM CONNECTOR. Turn ignition switch to OFF. Disconnect the connectors from drain valve and ECM. Measure the resistance of harness between drain valve connector and chassis ground. Connector & terminal (R143) No. 2 - Chassis ground:	Is the resistance more than 1 MΩ?	Go to step 4.	Repair short circuit to ground in harness between ECM and drain valve connector.
4. CHECK HARNESS BETWEEN DRAIN VALVE AND ECM CONNECTOR. Measure the resistance of harness between ECM and drain valve connector. Connector & terminal (B134) No. 13 - (R143) No. 2:	Is the resistance less than 1 Ω?	Go to step 5.	Repair harness and connector. NOTE: In this case, repair the following: Open circuit in harness between ECM and drain valve connector Poor contact in coupling connector
5. CHECK DRAIN VALVE. Measure the resistance between drain valve terminals. Terminals No. 1 - No. 2:	Is the resistance 10 - 100 Ω?	Go to step 6.	Replace the drain valve. < Ref. to DRAIN VALVE . >
6. CHECK POWER SUPPLY TO DRAIN VALVE. Turn ignition switch to ON. Measure the voltage between drain valve and chassis ground. Connector & terminal (R143) No. 1 (+) - Chassis ground (-):	Is the voltage more than 10 V?	Go to step 7.	Repair harness and connector. NOTE: In this case, repair the following: Open circuit in harness between main relay and drain valve Poor contact in coupling connector Poor contact in main relay connector
7. CHECK FOR POOR CONTACT. Check for poor contact in drain valve connector.	Is there poor contact in drain valve connector?	Repair poor contact in drain valve connector.	Contact SOA Service Center.

RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.