Subaru 2009 IMPREZA Service Manual page 1501

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
7 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 Monitor.>
• General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
8 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(H4DOTC)(diag)-34, Subaru Select Monitor.>
• General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
9 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) Open the front hood.
6) Measure the ambient temperature.
7) 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(H4DOTC)(diag)-34, Subaru Select Monitor.>
• General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Check
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)?
Subtract ambient temperature
from intake air temperature. Is
the obtained value –10 — 50°C
(–18 — 90°F)?
EN(H4DOTC)(diag)-280
Yes No
Go to step 8. Replace the
engine coolant
temperature sen-
sor. <Ref. to
FU(H4DOTC)-31,
Engine Coolant
Temperature Sen-
sor.>
Go to step 9. Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(H4DOTC)-39,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>
Go to step 10. Check the mass air
flow and intake air
temperature sen-
sor. <Ref. to
FU(H4DOTC)-39,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>