Subaru 2002 IMPREZA Service Manual page 535

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
Check
Does the Subaru Select Moni-
tor or OBD-II general scan tool
indicate DTC PO122 or P0123?
Step
1
CHECK ANY OTHER DTC ON DISPLAY.
Yes
Inspect DTC
PO1 22 or PO1 23
using "List of Diag-
nostic Trouble
Code (DTC)".
<Ref. to EN(D0HC
TURBO)-80, List
of Diagnostic Trou-
ble Code (DTC).>
NOTE:
In this case, it is
not necessary to
inspect DTC
P1142.
No
Replace the throt-
tle position sen-
sor. <Ref. to
FU(D0HC
Throttle Position
Sensor.
>
TURBO)-33,
EN(D0HC TURBO)-31 1