Subaru 2009 IMPREZA Service Manual page 696

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. <Ref. to
ME(H4SO)-27, INSPECTION, Fuel Pressure.>
CAUTION:
Release fuel pressure before removing the
fuel pressure gauge.
11 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(H4SO)(diag)-34, Subaru Select Moni-
tor.>
• General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
12 CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
1) Start the engine and warm up engine until
coolant temperature is higher than 75°C
(167°F).
2) For AT models, set the select lever to "P"
range or "N" range, and for MT models, place
the shift lever in the neutral position.
3) Turn the A/C switch to OFF.
4) Turn all the accessory switches to OFF.
5) Read the data of the mass air flow and
intake air temperature sensor signal using Sub-
aru Select Monitor or general scan tool.
NOTE:
• Subaru Select Monitor
For detailed operation procedures, refer to
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4SO)(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 333.4 —
360.5 kPa (3.4 — 3.7 kg/cm
48.4 — 52 psi)?
Is the engine coolant tempera-
ture 75°C (167°F) or higher?
Is the measured value 2.0 —
5.0 g/s (0.26 — 0.66 lb/m)?
EN(H4SO)(diag)-279
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 line
or bent hose
Fuel pressure is
too low:
• Improper fuel
pump discharge
• Clogged fuel line
Go to step 12. Replace the
engine coolant
temperature sen-
sor. <Ref. to
FU(H4SO)-25,
Engine Coolant
Temperature Sen-
sor.>
Go to step 13. Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(H4SO)-34,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
No