Nissan Repair: 2000 nissan xterra, nissan xterra, link error

Question
whats does the code p1605 means and whats the part needed for this  and is it expensive to fix

Answer
Tee,

A code P1605 is an A/T diagnostic communications link error.  Either the computer that shifts the transmission is defective or the harness that connects it to the main ECM is damaged.  If the vehicle was run through deep water or ran over something that could damage the harness.  Check to see if the overdrive light is flashing.  Email me back with what you find.  It is probably going to be the shift computer or a servo in the transmission.  If you desire Cottman Transmission has been good to me in the past for doing a diagnosis without taking advantage of me.