DTC P0447 Evaporative Emission Control System Vent Control Circuit Open

WARNING: This page is about a different car, the 2006 Subaru Outback. However, it is still accessible from the selected car via links, so may be relevant.

DTC DETECTING CONDITION:

Immediately at fault recognition
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, perform Clear Memory Mode < Ref. to OPERATION , Clear Memory Mode. > and Inspection Mode < Ref. to PROCEDURE , Inspection Mode. >.

WIRING DIAGRAM:

Fig 1: Evaporative Emission Control System Vent Control Circuit - Wiring Diagram

DTC P0447 EVAPORATIVE EMISSION CONTROL SYSTEM VENT CONTROL CIRCUIT OPEN - DIAGNOSTIC PROCEDURE

Step	Check	Yes	No
1 CHECK OUTPUT SIGNAL OF ECM. Turn the ignition switch to ON. Measure the voltage between ECM and chassis ground. Connector & terminal (B136) No. 17 (+) - Chassis ground (-):	Is the voltage more than 10 V?	Go to step 2.	Go to step 3.
2 CHECK POOR CONTACT. Check the poor contact of ECM connector.	Is there poor contact in ECM connector?	Repair the poor contact of ECM connector.	Even if the malfunction indicator light illuminates, the circuit has returned to a normal condition at this time. (However, the possibility of poor contact still remains.) NOTE: In this case, repair the following item: 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 the 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 the ground short circuit of 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 (B136) No. 17 - (R143) No. 2:	Is the resistance less than 1 Ω?	Go to step 5.	Repair the harness and connector. NOTE: In this case, repair the following item: 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 between 10 and 100 Ω?	Go to step 6.	Replace the drain valve. < Ref. to DRAIN VALVE . >
6 CHECK POWER SUPPLY TO DRAIN VALVE. Turn the 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 the harness and connector. NOTE: In this case, repair the following item: Open circuit in harness between main relay and drain valve Poor contact in coupling connector Poor contact in main relay connector
7 CHECK POOR CONTACT. Check for poor contact in the drain valve connector.	Is there poor contact in drain valve connector?	Repair poor contact in drain valve connector.	Contact with SOA Service Center.