Subaru IMPREZA 2004 Service Manual page 452

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
7 CHECK FUEL PRESSURE.
After connecting the pressure regulator vac-
uum hose, measure fuel pressure.
Warning:
Before removing the fuel pressure gauge,
release fuel pressure.
NOTE:
•If fuel pressure does not increase, squeeze
fuel return hose 2 to 3 times, then measure
fuel pressure again.
•If out of specification as measured at this step,
check or replace pressure regulator and pres-
sure regulator vacuum hose.
8 CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
1)Start the engine and warm-up completely.
2)Read the data of engine coolant temperature
sensor signal using Subaru Select Monitor or
OBD-II general scan tool.
NOTE:
•Subaru Select Monitor
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE".
<Ref. to EN(H4SO)(diag)-32, Subaru Select
Monitor.>
•OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Instruction Manual.
9 CHECK PRESSURE SENSOR SIGNAL.
1)Start the engine and warm-up engine until
coolant temperature is greater than 60°C
(140°F).
2)Place the select lever in "N" or "P" range.
3)Turn the A/C switch to OFF.
4)Turn all accessory switches to OFF.
5)Read the data of pressure sensor signal
using Subaru Select Monitor or OBD-II general
scan tool.
NOTE:
•Subaru Select Monitor
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE".
<Ref. to EN(H4SO)(diag)-32, Subaru Select
Monitor.>
•OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Instruction Manual.
Check
Is the fuel pressure 206 — 235
kPa (2.1 — 2.4 kg/cm
34 psi)?
Is the engine coolant tempera-
ture 70 — 100°C (158 —
212°F)?
Idling: Is the measured value
24.0 — 41.3 kPa (180 — 310
mmHg, 7.09 — 12.20 inHg)?,
Ignition ON: Is the measured
value 73.3 — 106.6 kPa (550
— 800 mmHg, 21.65 — 31.50
inHg)?
EN(H4SO)(diag)-143
ENGINE (DIAGNOSTICS)
Yes
Go to step 8.
2
, 30 —
Go to step 9.
Contact with SUB-
ARU distributor
service.
NOTE:
Inspection by DTM
is required, be-
cause probable
cause is deteriora-
tion of multiple
parts.
No
Repair the follow-
ing items.
Fuel pressure too
high
• Faulty pres-
sure regulator
• Clogged fuel
return line or
bent hose
Fuel pressure too
low
• Faulty pres-
sure regulator
• Improper fuel
pump discharge
• Clogged fuel
supply line
Replace the
engine coolant
temperature sen-
sor. <Ref. to
FU(H4SO)-27,
Engine Coolant
Temperature Sen-
sor.>
Replace the Pres-
sure sensor. <Ref.
to FU(H4SO)-33,
Manifold Absolute
Pressure Sensor.>