Subaru Legacy 2002 Service Manual page 1370

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
No.
2 CHECK ANY OTHER DTC ON DISPLAY.
Inspect DTC P0131, P0132, P0151 or P0152
using "List of Diagnostic Trouble Code
(DTC)". <Ref. to EN(H6)-87, List of Diagnostic
Trouble Code (DTC).>
3 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 rpm to 3,000 rpm
for two minutes.
2) Read data of rear oxygen sensor signal
using Subaru Select Monitor or OBD-II gen-
eral scan tool.
NOTE:
¼ Subaru Select Monitor
For detailed operation procedure, refer to the
"READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE". <Ref. to EN(H6)-38,
Subaru Select Monitor.>
¼ OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Instruction Manual.
4 CHECK REAR OXYGEN SENSOR DATA.
Read data of rear oxygen sensor signal using
Subaru Select Monitor or OBD-II General
Scan Tool.
5 CHECK HARNESS BETWEEN ECM AND
REAR OXYGEN SENSOR CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connectors from ECM and rear
oxygen sensor.
3) Measure resistance of harness between
ECM and rear oxygen sensor connector.
Connector & terminal
(B135) No. 19 — (T6) No. 4:
6 CHECK HARNESS BETWEEN REAR OXY-
GEN SENSOR AND ECM CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from rear oxygen
sensor.
3) Turn ignition switch to ON.
4) Measure voltage between rear oxygen sen-
sor harness connector and engine ground or
chassis ground.
Connector & terminal
(T6) No. 3 (+) — Engine ground (−):
Step
Is the failure cause of
P0131, P0132, P0151 or
P0152 in the fuel system?
Does the value fluctuate?
Is output maximum value
0.49 V or more and output
minimum value 0.25 V or
less?
Is the resistance more than
3 Ω?
Is the voltage more than
0.2 V?
EN(H6)-163
Check Yes
Check fuel sys-
tem.
NOTE:
In this case, it is
not necessary to
inspect DTC
P0137.
Go to step 7.
Go to step 5.
Repair open cir-
cuit in harness
between ECM
and rear oxygen
sensor connector.
Replace rear oxy-
gen sensor. <Ref.
to FU(H6)-46,
Rear Oxygen
Sensor.>
Engine (DIAGNOSTICS)
No
Go to step 3.
Go to step 4.
Replace rear oxy-
gen sensor. <Ref.
to FU(H6)-46,
Rear Oxygen
Sensor.>
Go to step 6.
Repair harness
and connector.
NOTE:
In this case,
repair the follow-
ing:
¼ Open circuit in
harness between
rear oxygen sen-
sor and ECM con-
nector
¼ Poor contact in
rear oxygen sen-
sor connector
¼ Poor contact in
ECM connector