Christian Fittipaldi of Brazil will replace Andretti beginning with this weekend's race at Michigan Speedway.
"Speed and Fittipaldi go together," Richard Petty said. "He knows how to run fast and he knows how to race fast. We feel he is going to do a great job for Petty Enterprises."
Andretti, the nephew of Mario Andretti and cousin of Michael Andretti, was in his second stint with the Petty Team. He drove 11 races in 1994 and returned to the team in 1998 to take over the No. 43 car Richard Petty made famous en route to seven Winston Cup titles.
In his second stint with Petty, Andretti won just one race and two poles. His best finish in the points standings was 11th in 1999.