DTC P04DB: Crankcase Ventilation System (PCV) Disconnected: Notes

1. -

DTC detecting condition:

Immediately at fault recognition

Trouble symptom:

Improper idling

Wiring diagram:

Engine Electrical System Ref. to WIRING SYSTEM>ENGINE ELECTRICAL SYSTEM

Courtesy of SUBARU OF AMERICA, INC.

CAUTION:

Use the check board when measuring the ECM terminal voltage and resistance. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>GENERAL DESCRIPTION>PREPARATION TOOL>HOW TO USE CHECK BOARD

NOTE:

After the faulty parts are repaired or replaced, perform the final check in Basic Diagnostic Procedure. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE

CHECK BLOW-BY HOSE .
Check the blow-by hose condition.

Is there any disconnection or crack in blow-by hose?

Yes : Install or replace the blow-by hose.

No : Go to 2.
CHECK HARNESS BETWEEN ECM AND BLOW-BY DIAGNOSIS CONNECTOR (OPEN) .
1. Turn the ignition switch to OFF.
2. Disconnect the connector from ECM.
3. Disconnect the connector from blow-by diagnosis connector.
4. Measure the resistance of harness between ECM connector and blow-by diagnosis connector.
  Connector & terminal
  
  (E51) No. 39 - (E79) No. 1:
  
  (E51) No. 33 - (E79) No. 2:
Is the resistance less than 1 Ω?

Yes : Go to 3.

No : Repair the following item.
- Open circuit in harness between ECM connector and blow-by diagnosis connector
- Poor contact of coupling connector
- Poor contact of J/C
CHECK HARNESS BETWEEN ECM AND BLOW-BY DIAGNOSIS CONNECTOR (SHORT TO GROUND) .
Measure the resistance between the blow-by diagnosis connector and engine ground.

Connector & terminal

(E51) No. 33 - Engine ground:

(E51) No. 39 - Engine ground:

Is the resistance 1 MΩ or more?

Yes : Go to 4.

No : Repair the short circuit to ground in harness between ECM connector and blow-by diagnosis connector.
CHECK PCV HOSE ASSEMBLY .
Measure the resistance between blow-by diagnosis connector terminals.

Terminals

No. 1 - No. 2:

Is the resistance less than 1 Ω?

Yes : Repair the poor contact of ECM and blow-by diagnosis connector.

No : Replace the PCV hose assembly. Ref. to EMISSION CONTROL (AUX. EMISSION CONTROL DEVICES) (H4DOTC)>PCV HOSE ASSEMBLY