Subaru 2009 IMPREZA Service Manual page 152

15.Front Oxygen (A/F) Sensor
A: REMOVAL
1) Set the vehicle on a lift.
2) Disconnect the ground cable from battery.
3) Remove the air intake duct. <Ref. to IN(H4SO)-
8, REMOVAL, Air Intake Duct.>
4) Remove the clip fastening the harness and dis-
connect the front oxygen (A/F) sensor connector.
(B)
(C)
(A) Front oxygen (A/F) sensor connector
(B) Rear oxygen sensor connector
(C) Clip
5) Lift up the vehicle.
6) Remove the under cover.
7) Apply spray-type lubricant to the threaded por-
tion of front oxygen (A/F) sensor, and leave it for
one minute or more.
Front Oxygen (A/F) Sensor
8) Remove the front oxygen (A/F) sensor.
CAUTION:
When removing the front oxygen (A/F) sensor,
wait until exhaust pipe cools, otherwise it will
damage the exhaust pipe.
IN-00203
B: INSTALLATION
(A) CAUTION:
If lubricant is spilt onto the exhaust pipe, wipe it
off completely with cloth to avoid emission of
smoke or causing a fire.
1) Before installing front oxygen (A/F) sensor, ap-
ply anti-seize compound only to the threaded por-
tion of front oxygen (A/F) sensor to make the next
removal easier.
CAUTION:
EX-02350
Never apply anti-seize compound to the protec-
tor of front oxygen (A/F) sensor.
Anti-seize compound:
2) Install the front oxygen (A/F) sensor.
Tightening torque:
FU(H4SO)-41
FUEL INJECTION (FUEL SYSTEMS)
(B)
(A)
(A) Front oxygen (A/F) sensor
(B) Rear oxygen sensor
NEVER-SEEZ NSN, JET LUBE SS-30 or
equivalent
21 N·m (2.1 kgf-m, 15.5 ft-lb)
(B)
(A)
(A) Front oxygen (A/F) sensor
(B) Rear oxygen sensor
FU-02735
FU-02735