Subaru IMPREZA 2004 Service Manual page 15

(1) Front oxygen (A/F) sensor
(2) Rear oxygen sensor
(3)
Electrical Components Location
(3) Front catalytic converter
(1)
EN-00014
EN-00016
EN(H4SO)(diag)-13
ENGINE (DIAGNOSTICS)
(4) Rear catalytic converter
EN-00162
EN-00163
EN-00164