The Martian · Andy Weir, 2011
How far is Pathfinder from the Hab in The Martian?
~800km
Pathfinder sits about 800 km south of the Hab, near the mouth of Ares Vallis.
From the bookReal world
Watney needs a radio, and the nearest one is on Pathfinder, the lander that came down in 1997. He rigs a rover with extra batteries, navigates by Phobos, drives south for about ten sols, and digs the lander out of the sand.
Pathfinder's landing site on the map is the real one, at 19.13° N 33.22° W. The Hab is where the book puts it, at 31.2° N 28.5° W. The route between them, and most of the sol numbers, are the map's guesses.
Back at the Hab he gets Pathfinder's camera working and talks to NASA with hexadecimal cards. That trip was the test run for the much longer drive later: about 3,235 km to Schiaparelli.
See the drive to Pathfinder