Subaru Legacy 2004 Service Manual page 555

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
5 CHECK EXHAUST SYSTEM.
Check exhaust system parts.
NOTE:
Check the following items:
• Loose part of exhaust system and incom-
plete installation
• Damage (crack, hole etc.) of parts
• Looseness and ill fitting of parts between
front oxygen (A/F) sensor and rear oxygen
sensor
Check
Is there any fault in exhaust
system?
EN(H4SO 2.0)(diag)-123
ENGINE (DIAGNOSTICS)
Yes
Repair or replace Replace the rear
the faulty part. oxygen sensor.
<Ref. to FU(H4SO
2.0)-33, Rear Oxy-
gen Sensor.>
No