Subaru 2009 IMPREZA Service Manual page 1536

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
9 CHECK AIR INTAKE SYSTEM.
10 CHECK FUEL PRESSURE.
WARNING:
Place "NO OPEN FLAMES" signs near the
working area.
CAUTION:
Be careful not to spill fuel.
1) Connect the front oxygen (A/F) sensor con-
nector.
2) Measure the fuel pressure while discon-
necting pressure regulator vacuum hose from
intake manifold. <Ref. to ME(H4DOTC)-25,
INSPECTION, Fuel Pressure.>
CAUTION:
Release fuel pressure before removing the
fuel pressure gauge.
NOTE:
If fuel pressure does not increase, squeeze the
fuel return hose 2 to 3 times, then measure fuel
pressure again.
11 CHECK FUEL PRESSURE.
After connecting the pressure regulator vacuum
hose, measure fuel pressure. <Ref. to
ME(H4DOTC)-25, INSPECTION, Fuel Pres-
sure.>
CAUTION:
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 regula-
tor and pressure regulator vacuum hose.
12 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 procedures, refer to
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4DOTC)(diag)-34, Subaru Select Moni-
tor.>
• General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Check
Are there holes, loose bolts or
disconnection of hose on air
intake system?
Is the measured value 284 —
314 kPa (2.9 — 3.2 kgf/cm
41 — 46 psi)?
Is the measured value 230 —
260 kPa (2.35 — 2.65 kgf/cm
33 — 38 psi)?
Is the engine coolant tempera-
ture 75°C (167°F) or higher?
EN(H4DOTC)(diag)-315
ENGINE (DIAGNOSTICS)
Yes
Repair the air Go to step 10.
intake system.
Go to step 11. Repair the follow-
2
, ing item.
Fuel pressure is
too high:
• Clogged fuel
return line or bent
hose
Fuel pressure is
too low:
• Improper fuel
pump discharge
• Clogged fuel
supply line
Go to step 12. Repair the follow-
2
, ing item.
Fuel pressure is
too high:
• Faulty pressure
regulator
• Clogged fuel
return line or bent
hose
Fuel pressure is
too low:
• Faulty pressure
regulator
• Improper fuel
pump discharge
• Clogged fuel
supply line
Go to step 13. Replace the
engine coolant
temperature sen-
sor. <Ref. to
FU(H4DOTC)-31,
Engine Coolant
Temperature Sen-
sor.>
No