Mark McNabb is leaving Nissan North America Inc. at the end of the month, marking the second time the auto maker will lose its top U.S. sale executive since it moved its headquarters to Nashville, TN.

Nissan says McNabb, senior vice president sales and marketing, is leaving for personal reasons. Press reports indicate he may be headed for a Detroit-based auto maker.

Replacing McNabb is Brian Carolin, currently senior vice president-sales and marketing for Nissan Europe. Carolin joined Nissan U.K. in 1984 and has held various jobs in human resources, purchasing and product planning before moving to his current position in January 2005.

Nissan also announced Tsuyoshi Yamaguchi, currently president of the Michigan-based Nissan Technical Center North America, will be promoted to a yet-to-be-announced senior position at its Tokyo headquarters. He will be succeeded by Motohiro Matsumura, currently general manager-vehicle test department for the Nissan Technical Center in Japan.

“We regret but respect Mark’s decision to leave the company and thank him for his contributions over the previous 20 years to Nissan’s success in North America,” Hiroto Saikawa, executive vice president-purchasing for Nissan Motor Co. Ltd., says in relation to McNabb.

McNabb has held the top sales job in the U.S. for less than a year. He replaced Brad Bradshaw last June after Bradshaw’s sudden, unexpected departure. Bradshaw had occupied the position for just over a year, having replaced Jed Connelly in March 2006 after Connelly decided against moving with the auto maker from California to Nashville.

McNabb was on his second tour of duty at Nissan. He spent nearly 20 years there before defecting to Mercedes-Benz U.S.A. in 2005. He returned to Nissan in April 2007 to head global business for the Infiniti brand.

Nissan total sales, including Infiniti, are off 3.0% so far this year. Last year, deliveries rose 4.8%.