Subaru 2002 IMPREZA Service Manual page 1357

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
1 CHECK ANY OTHER DIAGNOSTIC TROU-
BLE CODE (DTC) ON DISPLAY.
2 CHECK EXHAUST SYSTEM.
Check for gas leaks or air suction caused by
loose or dislocated nuts and bolts, and open
hole at exhaust pipes.
NOTE:
Check the following positions.
•Between cylinder head and front exhaust pipe
•Between front exhaust pipe and front catalytic
converter
•Between front catalytic converter and rear cat-
alytic converter
3 CHECK REAR CATALYTIC CONVERTER.
Separate the rear catalytic converter from rear
exhaust pipe.
4 CHECK FRONT CATALYTIC CONVERTER.
Remove the front catalytic converter.
Check
Is any other DTC displayed?
Is there a fault in exhaust sys-
tem?
Is there damage at rear face of
rear catalyst?
Is there damage at rear face or
front face of front catalyst?
EN(TURBO)-197
ENGINE (DIAGNOSTICS)
Yes
Inspect the rele- Go to step 2.
vant DTC using
"List of Diagnostic
Trouble Code
(DTC)". <Ref. to
EN(TURBO)-75,
List of Diagnostic
Trouble Code
(DTC).>
NOTE:
In this case, it is
not necessary to
inspect DTC
P0420.
Repair or replace Go to step 3.
the exhaust sys-
tem. <Ref. to
EX(TURBO)-2,
General Descrip-
tion.>
Replace the front Go to step 4.
catalytic con-
verter. <Ref. to
EC(TURBO)-3,
Front Catalytic
Converter.> and
rear catalytic con-
verter <Ref. to
EC(TURBO)-4,
Rear Catalytic
Converter.>
Replace the front Contact with your
catalytic con- Subaru distributor
verter. <Ref. to service.
EC(TURBO)-3,
NOTE:
Front Catalytic
Inspection by DTM
Converter.>
is required,
cause
cause is deteriora-
tion of
parts.
No
be-
probable
multiple