Subaru Impreza 2003 Service Manual page 1291

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
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 the
OBD-II general scan tool.
NOTE:
•Subaru Select Monitor
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE".
<Ref. to EN(H4DOTC)-32, Subaru Select Mon-
itor.>
•OBD-II general scan tool
For detailed operation procedure, refer to the
OBD-II General Scan Tool Instruction Manual.
2 CHECK HARNESS BETWEEN MASS AIR
FLOW AND INTAKE AIR TEMPERATURE
SENSOR AND ECM CONNECTOR.
1)Turn the ignition switch to OFF.
2)Disconnect the connector from mass air flow
and intake air temperature sensor.
3)Turn the ignition switch to ON.
4)Read the data of intake air temperature sen-
sor signal using Subaru Select Monitor or the
OBD-II general scan tool.
NOTE:
•Subaru Select Monitor
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE".
<Ref. to EN(H4DOTC)-32, Subaru Select Mon-
itor.>
•OBD-II general scan tool
For detailed operation procedure, refer to the
OBD-II General Scan Tool Instruction Manual.
Check
Is the temperature more than
55°C (131°F)?
Is the temperature less than
−36°C (−33°F)?
EN(H4DOTC)-115
ENGINE (DIAGNOSTICS)
Yes
Go to step 2. Repair the poor
contact.
NOTE:
In this case, repair
the following:
• Poor contact
mass air flow and
intake air tempera-
ture sensor
• Poor contact in
ECM
• Poor contact in
joint connector
Replace the mass Repair the ground
air flow and intake short circuit in har-
air temperature ness between
sensor. <Ref. to mass air flow and
FU(H4DOTC)-34, intake air tempera-
Mass Air Flow and ture sensor and
Intake Air Temper- ECM connector.
ature Sensor.>
No