Subaru IMPREZA 2002 Service Manual page 460

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
I Yes No
In this case, it is
not necessary to
inspect DTC
~
PO1 28.
Go to step 3.
Go to step 2.
Inspect DTC
PO1 25, P0301,
P0302, PO303 and
PO304 using "List
of Diagnostic Trou-
ble Code (DTC)".
<Ref. to
List of Diagnostic
Trouble Code
I
I
EN(S0HC)-77,
T:
DTC DETECTING CONDITION:
TROUBLE SYMPTOM:
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(S0HC)-43, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(S0HC)-40, OPERATION, Inspec-
tion Mode.>.
DTC PO128
-
THERMOSTAT MALFUNCTION
-
Two consecutive driving cycles with
fault
Thermostat remains open.
Go to step 4.
I
Repair radiator fan
hircuit. <Ref. to
CO-46, Radiator
Main Fan and Fan
,Motor.> and <Ref.
to CO-48, Radiator
Sub Fan and Fan
Motor.>
Step
CHECK VEHICLE CONDITION.
(DTC).>
Replace the
engine coolant.
<Ref. to CO-25,
REPLACEMENT,
Engine Coolant.>
Replace the ther-
mostat. <Ref. to
CO-35, Thermo-
stat.>
CHECK ANY OTHER DTC ON DISPLAY.
CHECK ENGINE COOLANT.
CHECK RADIATOR FAN.
1)Start the engine.
2)Check radiator fan operation.
Check
Has engine operated at idle or
has vehicle been driven with
part of engine submerged
under water?
Does the Subaru Select Moni-
tor or OBD-lI general scan tool
indicate DTC PO1 25, P0301,
P0302, PO303 and PO304 at
same time?
Are cootant level and mixture
ratio of cooling water to anti-
freeze solution correct?
Does the radiator fan continu-
ously rotate for more than 3
minutes during idling?
EN(S0HC)-136