Subaru Legacy 2003 Service Manual page 539

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
5 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR.
Measure resistance between ECM and chas-
sis ground.
Connector & terminals
(B136) No. 13 — Chassis ground:
(B136) No. 22 — Chassis ground:
Does the measured value exceed the specified
value?
6 CHECK EXHAUST SYSTEM.
Check exhaust system parts.
Is there a fault in exhaust system?
NOTE:
Check the following items.
•Loose installation of portions
•Damage (crack, hole etc.) of parts
•Looseness of front oxygen (A/F) sensor
•Looseness and ill fitting of parts between front
oxygen (A/F) sensor and rear oxygen sensor
Step
EN(H4SO)-142
Value
1 MΩ
There is a fault.
Yes
Go to step 6. Repair ground
short circuit
between ECM and
front oxygen (A/F)
sensor.
Repair or replace Replace front oxy-
faulty parts. gen (A/F) sensor.
<Ref. to
FU(H4SO)-41,
Front Oxygen (A/
F) Sensor.>
No