Wiring Diagram:

WARNING: This page is about a different variant/trim than selected.

Fig 1: Wiring Diagram - DTC P1491 Positive Crankcase Ventilation (Blow-By) Function Problem

G03830040

Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSTIC PROCEDURE (DTC P1491)

Step		Check	Yes	No
1 CHECK BLOW-BY HOSE. Check the blow-by hose.		Is there disconnection or crack in blow-by hose?	Replace or repair blow-by hose.	Go to step 2.
2 CHECK HARNESS BETWEEN PCV HOSE ASSEMBLY AND ECM CONNECTOR. Turn the ignition switch to OFF. Disconnect the connector from PCV hose assembly and ECM. Measure the resistance of harness between PCV hose assembly and ECM connector. Connector & terminal (B137) No. 24 - (E61) No. 2:		Is the resistance less than 1 ?	Go to step 3.	Repair open circuit in harness between PCV hose assembly and ECM.
3 CHECK HARNESS BETWEEN PCV HOSE ASSEMBLY AND ECM CONNECTOR. Measure the resistance of harness between PCV hose assembly and chassis ground. Connector & terminal (B137) No. 24 - Chassis ground:		Is the resistance more than 1 M?	Go to step 4.	Repair short circuit to chassis ground in harness between PCV hose assembly and ECM.
4 CHECK PCV HOSE ASSEMBLY GROUND CIRCUIT. Measure the resistance between PCV hose assembly and engine ground. Connector & terminal (B61) No. 1 - Engine ground:		Is the resistance less than 5 ?	Go to step 5.	Repair PCV hose assembly ground circuit.
5 CHECK PCV HOSE ASSEMBLY. Measure the resistance between PCV hose assembly and terminal. Terminals No. 1 - No. 2:		Is the resistance less than 1 ?	Repair poor contact in ECM and PCV hose assembly.	Replace PCV hose assembly.