Subaru Legacy 2005 Service Manual page 1352

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
4 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
specifications, check or replace the pressure
regulator and pressure regulator vacuum hose.
5 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 Monitor
or general scan tool.
NOTE:
• Subaru Select Monitor
For detailed operation procedure, refer to
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4DOTC)(diag)-24, Subaru Select Mon-
itor.>
• General scan tool
For detailed operation procedure, refer to the
general scan tool operation manual.
6 CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
1) Start and warm-up the engine until engine
coolant temperature is above 60°C (140°F).
2) Place the shift lever in neutral position.
3) Turn the A/C switch to OFF.
4) Turn all the accessory switches to OFF.
5) Read the data of mass air flow and intake
air temperature sensor signal using Subaru
Select Monitor or general scan tool.
NOTE:
• Subaru Select Monitor
For detailed operation procedure, refer to
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4DOTC)(diag)-24, Subaru Select Mon-
itor.>
• General scan tool
For detailed operation procedure, refer to the
general scan tool operation manual.
Check
Is the measured value 206 —
235 kPa (2.1 — 2.4 kgf/cm
— 34 psi)?
Is the temperature more than
60°C (140°F)?
Is the measured value within
the following? Ignition ON: 73.3
— 106.6 kPa (550 — 800
mmHg, 21.65 — 31.50 inHg)
Idling: 24.0 — 41.3 kPa (180 —
310 mmHg, 7.09 — 12.20
inHg)
EN(H4DOTC)(diag)-112
Yes
Go to step 5. Repair the follow-
ing items.
2
, 30
Fuel pressure is
too high:
Fuel pressure is
too low:
Go to step 6. Replace the
engine coolant
temperature sen-
sor. <Ref. to
FU(H4DOTC)-22,
Engine Coolant
Temperature Sen-
sor.>
Go to step 7. Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(H4DOTC)-27,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
No
• Faulty pres-
sure regulator
• Clogged fuel
return line or
bent hose
• Faulty pres-
sure regulator
• Improper fuel
pump discharge
• Clogged fuel
supply line