Subaru IMPREZA 2004 Service Manual page 727

3) When the ignition switch is turned to ON (engine
off) or to START with the test mode connector con-
nected, the malfunction indicator light blinks at a
cycle of 3 Hz.
(A)
(1)
(2)
(4)
(A) Malfunction indicator light when no trouble
(1) ON
(2) OFF
(3) 1 sec.
(4) Ignition switch ON
Malfunction Indicator Light
(3)
EN-01545
EN(H4SOw/oOBD)(diag)-31
ENGINE (DIAGNOSTICS)