Subaru 2009 IMPREZA Service Manual page 974

7) Connect the ground cable to battery.
C: INSPECTION
Measure the resistance between front oxygen (A/F)
sensor terminal.
1 2
3 4
Terminal No.
1 and 2
Front Oxygen (A/F) Sensor
IN-00203
FU-04072
Standard
2.4 0.24 (20°C (68°F))
FU(H4DOTC)-49
FUEL INJECTION (FUEL SYSTEMS)