Subaru 2009 IMPREZA Service Manual page 1771

Diagnostic Trouble Code (DTC) Detecting Criteria
CU:DTC P1491 POSITIVE CRANKCASE VENTILATION (BLOW-BY) FUNCTION
PROBLEM
1. OUTLINE OF DIAGNOSIS
Detect the blow-by hose release abnormality.
Judge as NG when the diagnosis terminal voltage is high.
2. COMPONENT DESCRIPTION
(1)
(1) Engine control module (ECM)
(2) Detecting circuit
3. ENABLE CONDITIONS
Secondary Parameters
None
4. GENERAL DRIVING CYCLE
Always perform the diagnosis continuously.
(4)
(2)
(3) PCV diagnosis connector
Enable Conditions
GD(H4DOTC)-183
(3)
(4) 5 V
GENERAL DESCRIPTION
E
EN-01790