Subaru Impreza 2004 Service Manual page 140

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 CHECK CURRENT DATA.
1)Start the engine.
2)Read the data of exhaust gas temperature
sensor signal using Subaru Select Monitor or
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)(diag)-32, Subaru
Select Monitor.>
•OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Instruction Manual.
2 CHECK HARNESS BETWEEN EXHAUST
GAS TEMPERATURE SENSOR AND ECM
CONNECTOR.
1)Turn the ignition switch to OFF.
2)Disconnect the connector from exhaust gas
temperature sensor.
3)Measure the voltage between exhaust gas
temperature sensor connector and engine
ground.
Connector & terminal
(B279) No. 1 (+) — Engine ground ( − − − − ):
3 CHECK HARNESS BETWEEN EXHAUST
GAS TEMPERATURE SENSOR AND ECM
CONNECTOR.
1)Turn the ignition switch to ON.
2)Measure the voltage between exhaust gas
temperature sensor connector and engine
ground.
Connector & terminal
(B279) No. 1 (+) — Engine ground ( − − − − ):
4 CHECK HARNESS BETWEEN EXHAUST
GAS TEMPERATURE SENSOR AND ECM
CONNECTOR.
Measure the voltage between exhaust gas
temperature sensor connector and engine
ground.
Connector & terminal
(B279) No. 1 (+) — Engine ground ( − − − − ):
Check
Is the temperature less than
372°C (702°F)?
Is the voltage more than 10 V? Repair the battery
Is the voltage more than 10 V? Repair the battery
Is the voltage more than 4 V?
EN(H4DOTC)(diag)-219
ENGINE (DIAGNOSTICS)
Yes
Go to step 2. Repair the poor
contact.
NOTE:
In this case, repair
the following:
• Poor contact in
exhaust gas tem-
perature sensor
• Poor contact in
ECM
• Poor contact in
joint connector
Go to step 3.
short circuit in har-
ness between
ECM and exhaust
gas temperature
sensor connector.
Go to step 4.
short circuit in har-
ness between
ECM and exhaust
gas temperature
sensor connector.
Go to step 5. Repair the har-
ness and connec-
tor.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
ECM and exhaust
gas temperature
sensor connector
• Poor contact in
exhaust gas tem-
perature sensor
connector
• Poor contact in
ECM connector
• Poor contact in
joint connector
No