Subaru 2009 IMPREZA Service Manual page 547

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of intake air temperature sen-
sor signal using Subaru Select Monitor or gen-
eral 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.
2 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW AND INTAKE AIR TEM-
PERATURE SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
the mass air flow and intake air temperature
sensor.
3) Measure the resistance between ECM and
chassis ground.
Connector & terminal
(B135) No. 18 — Chassis ground:
Check
Is the intake air temperature
120°C (248°F) or more?
Is the resistance 1 M or
more?
EN(H4SO)(diag)-130
Yes No
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector
may be the cause.
Replace the mass Repair the short
air flow and intake circuit to ground in
air temperature harness between
sensor. <Ref. to ECM and the mass
FU(H4SO)-34, air flow and intake
Mass Air Flow and air temperature
Intake Air Temper- sensor connector.
ature Sensor.>