Subaru Legacy 2002 Service Manual page 794

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
No.
2 CHECK ACCESSORY.
Step
Are car phone and/or CB
installed on vehicle?
EN-277
Check Yes
Repair grounding
line of car phone
or CB system.
Engine (Diagnostics)
No
Replace TCM.
<Ref. to AT-49,
Transmission
Control Module
(TCM).>