Subaru Legacy 2004 Service Manual page 2312

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AUTOMATIC TRANSMISSION (DIAGNOSTICS)
AA:DTC P1718 CAN COMMUNICATION CIRCUIT
NOTE:
Refer to "Body Integrated Unit" for diagnosis of P1718. <Ref. to LAN(diag)-2, Basic Diagnostic Procedure.>
4AT(diag)-109