Subaru IMPREZA GD 2007 Series Manual page 216

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Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of air flow sensor signal using
the 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)-32, Subaru Select Monitor.>
• General scan tool
For detailed operation procedure, refer to the
general scan tool operation manual.
2 CHECK HARNESS BETWEEN ECM AND
THE MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR CONNECTORS.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the mass air
flow and intake air temperature sensor.
3) Start the engine.
4) Read the data of air flow sensor signal using
the 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)-32, Subaru Select Monitor.>
• General scan tool
For detailed operation procedure, refer to the
general scan tool operation manual.
3 CHECK HARNESS BETWEEN ECM AND
THE MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR CONNECTORS.
1) Turn the ignition switch to OFF.
2) Measure the resistance of harness between
mass air flow and intake air temperature sensor
connector and engine ground.
Connector & terminal
(B3) No. 2 — Engine ground:
4 CHECK POOR CONTACT.
Check for any poor contact between the mass
air flow and intake air temperature sensor con-
nectors.
Check
Is the voltage 5 V or more?
Is the voltage 5 V or more?
Is the resistance less than 5 Ω? Go to step 4.
Is there poor contact in the
mass air flow and intake air
temperature sensor connec-
tors?
EN(H4SO)(diag)-107
ENGINE (DIAGNOSTICS)
Yes No
Go to step 2. Even if the malfunc-
tion indicator light
illuminates, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the fault con-
dition, and
reperform the
check.
NOTE:
In this case, there
may be a tempo-
rary connector
contact failure.
Repair the short Go to step 3.
circuit to power in
the harness
between the ECM
and the mass air
flow and intake air
temperature sen-
sor connectors.
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
• Open circuit of
harness between
the ECM and the
mass air flow and
intake air tempera-
ture sensor con-
nectors
• Poor contact in
ECM connector
Repair any poor Replace the mass
contact of the air flow and intake
mass air flow and air temperature
intake air tempera- sensor. <Ref. to
ture sensor con- FU(H4SO)-28,
nectors. Mass Air Flow and
Intake Air Temper-
ature Sensor.>