Subaru 2004 LEGACY Service Manual page 96

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 out of specification as measured at this
step, check or replace pressure regulator 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 procedures, refer to the
"READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE". <Ref. to EN(H6DO)(di-
ag)-25, Subaru Select Monitor.>
9 CHECK MANIFOLD PRESSURE SENSOR
SIGNAL.
1) Start and warm-up the engine until engine
coolant temperature is greater than 60°C
(140°F).
2) Shift the select lever to "N" or "P" range.
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 procedures, refer to the
"READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE". <Ref. to EN(H6DO)(di-
ag)-25, Subaru Select Monitor.>
Check
Is fuel pressure 279 — 309
kPa (2.85 — 3.15 kg/cm
— 45 psi)?
Is the engine coolant tempera-
ture 70 — 100°C (158 —
212°F)?
Is the measurement value at
idling: 24.0 — 41.3 kPa (180 —
310 mmHg, 7.09 — 12.20
inHg), when ignition ON: 73.3
— 106.6 kPa (550 — 800
mmHg, 21.65 — 31.50 inHg)?
EN(H6DO)(diag)-165
ENGINE (DIAGNOSTICS)
Yes
Go to step 8.
2
, 40
Go to step 9.
Replace the ECM.
<Ref. to
FU(H6DO)-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(H6DO)-18,
Engine Coolant
Temperature Sen-
sor.>
Replace the mani-
fold absolute pres-
sure sensor. <Ref.
to FU(H6DO)-23,
Manifold Absolute
Pressure Sensor.>