Subaru Legacy 2004 Service Manual page 559

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
7 CHECK FUEL PRESSURE.
After connecting the pressure regulator vac-
uum hose, measure fuel pressure.
Warning:
Release fuel pressure before removing the
fuel pressure gauge,.
NOTE:
• If fuel pressure does not increase, squeeze
fuel return hose 2 to 3 times, then measure
fuel pressure again.
• If the measured value at this step is out of
specification, check or replace pressure regu-
lator and pressure regulator vacuum hose.
8 CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
1) Start the engine and warm-up completely.
2) Read the data of engine coolant tempera-
ture sensor signal using Subaru Select Moni-
tor.
NOTE:
For detailed operation procedure, refer to
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4SO 2.0)(diag)-25, Subaru Select Mon-
itor.>
9 CHECK MANIFOLD PRESSURE SENSOR
SIGNAL.
1) Start and warm-up the engine until engine
coolant temperature is above 60!C (140!F).
2) Place the select lever in "N" or "P" position.
3) Turn the A/C switch to OFF.
4) Turn all accessory switches to OFF.
5) Read the data of manifold pressure sensor
signal using Subaru Select Monitor.
NOTE:
For detailed operation procedure, refer to
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4SO 2.0)(diag)-25, Subaru Select Mon-
itor.>
Check
Is measured value 206 — 235
kPa (2.1 — 2.4 kg/cm
34 psi)?
Is the engine coolant tempera-
ture 70 — 100!C (158 —
212!F)?
Is the measurement value 24.0
— 41.3 kPa (180 — 310
mmHg, 7.09 — 12.20 inHg)
when idling and 73.3 — 106.6
kPa (550 — 800 mmHg, 21.65
— 31.50 inHg) when the igni-
tion turns to ON?
EN(H4SO 2.0)(diag)-127
ENGINE (DIAGNOSTICS)
Yes
Go to step 8.
2
, 30 —
Go to step 9.
Replace the ECM.
<Ref. to FU(H4SO
2.0)-34, Engine
Control Module
(ECM).>
No
Repair the follow-
ing items.
Fuel pressure is
too high:
• Faulty pres-
sure regulator
• Clogged fuel
return line or
bent hose
Fuel pressure is
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 2.0)-20,
Engine Coolant
Temperature Sen-
sor.>
Replace the mani-
fold pressure sen-
sor. <Ref. to
FU(H4SO 2.0)-26,
Manifold Absolute
Pressure Sensor.>