DTC P1491 Positive Crankcase Ventilation (Blow-By) Function Problem: Wiring Diagram
WARNING: This page is about a different car, the 2012 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.
DIAGNOSIS PROCEDURE
| Step | Check | Yes | No |
|---|---|---|---|
| 1 CHECK BLOW-BY HOSE. Check the blow-by hose condition. |
Is there any disconnection or crack in blow-by hose? | Repair or replace the blow-by hose. | Go to step 2 . |
2 CHECK HARNESS BETWEEN ECM AND PCV HOSE ASSEMBLY CONNECTOR.
|
Is the resistance less than 1 Ω? | Go to step 3 . | Repair the harness and connector.
NOTE:
In this case, repair the following item:
|
| 3 CHECK HARNESS BETWEEN ECM AND PCV HOSE ASSEMBLY CONNECTOR. Measure the resistance between PCV hose assembly connector and chassis ground. Connector & terminal (B137) No. 12 - Chassis ground: |
Is the resistance 1 MΩ or more? | Go to step 4 . | Repair the short circuit to ground in harness between ECM and PCV hose assembly connector. |
| 4 CHECK GROUND CIRCUIT OF PCV HOSE ASSEMBLY. Measure the resistance of harness between PCV hose assembly connector and engine ground. Connector & terminal (E80) No. 1 - Engine ground: |
Is the resistance less than 5 Ω? | Go to step 5 . | Repair the harness and connector.
NOTE:
In this case, repair the following item:
|
| 5 CHECK PCV HOSE ASSEMBLY. Measure the resistance between the PCV hose assembly terminals. Terminals No. I - No. : |
Is the resistance less than 1 Ω? | Repair the poor contact of ECM and PCV hose assembly connector. | Replace the PCV hose assembly. |