The most common problems that occur in the 2001 Nissan Pathfinder, according to reviews at Edmunds.com, are CD changer failures, mass air flow sensor failures and oxygen sensor issues. Less common failures are windshield washer motors, wheel bearings and tie rod ends.
Other reviewers also mentioned underbody or exhaust system rust, but the writers admitted their locations exposed them to much road salt in the winter. Some reviewers mentioned strut replacements, while only one had a strut tower failure, which may be the same issue.
Other owners made reference to cheap interior parts and catalytic converter failures. Injector failures were also mentioned but appeared to be an uncommon problem.