Subaru Impreza 2004 Service Manual page 172

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
2 CHECK ACCESSORY.
Check
Are car phone and/or CB
installed on vehicle?
EN(H4DOTC)(diag)-251
ENGINE (DIAGNOSTICS)
Yes
Repair the ground- Replace the TCM.
ing line of car <Ref. to 4AT-74,
phone or CB sys- Transmission Con-
tem. trol Module
(TCM).>
No