Subaru Legacy 2005 Service Manual page 1349

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 CHECK ANY OTHER DTC ON DISPLAY.
2 CHECK REAR OXYGEN SENSOR DATA.
1) Warm-up the engine until engine coolant
temperature is above 70°C (158°F), and keep
the engine speed at 2,000 to 3,000 rpm for two
minutes.
2) Read the data of rear oxygen sensor signal
using Subaru Select Monitor or general scan
tool.
NOTE:
• Subaru Select Monitor
For detailed operation procedure, refer to
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4DOTC)(diag)-24, Subaru Select Mon-
itor.>
• General scan tool
For detailed operation procedure, refer to the
general scan tool operation manual.
3 CHECK REAR OXYGEN SENSOR DATA.
Read the data of rear oxygen sensor signal
using Subaru Select Monitor or general scan
tool.
NOTE:
• Subaru Select Monitor
For detailed operation procedure, refer to
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4DOTC)(diag)-24, Subaru Select Mon-
itor.>
• General scan tool
For detailed operation procedure, refer to the
general scan tool operation manual.
4 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
rear oxygen sensor.
3) Measure the resistance of harness
between ECM and rear oxygen sensor con-
nector.
Connector & terminal
(B137) No. 25 — (T6) No. 4:
Check
Is any other DTC displayed?
Does the value fluctuate?
Is the voltage 0.2 — 0.4 V?
Is the resistance more than 3
Ω?
EN(H4DOTC)(diag)-109
ENGINE (DIAGNOSTICS)
Yes
Check DTC using Go to step 2.
"List of Diagnostic
Trouble Code
(DTC)". <Ref. to
EN(H4DOTC)(diag
)-62, List of Diag-
nostic Trouble
Code (DTC).>
Go to step 6. Go to step 3.
Go to step 4. Replace the rear
oxygen sensor.
<Ref. to
FU(H4DOTC)-33,
Rear Oxygen Sen-
sor.>
Repair the open Go to step 5.
circuit of harness
between ECM and
rear oxygen sen-
sor connector.
No