DETROIT — Stellantis has appointed a new head of purchasing and supply chain in North America amid deteriorating relations with its suppliers.

Marlo Vitous, 45, the company’s supply chain vice president, is replacing Martin Horneck, who is retiring, two sources with knowledge of the matter told Automotive News. Horneck, 59, had been hired by Fiat Chrysler Automobiles in 2020 ahead of the merger with PSA Group that formed Stellantis.

Stellantis confirmed Horneck’s departure Tuesday but did not comment further.

The change comes shortly after Stellantis created controversy among its suppliers with new purchasing terms and conditions that it later rescinded — and one day after a prominent study gauging suppliers’ relationship with major automakers ranked the company lowest for a second consecutive year.

In Plante Moran’s annual Working Relations Index released Monday, Stellantis dropped to the study’s lowest ranking for any North American automaker in more than a decade. FCA had received low marks in the study even before the January 2021 merger with PSA.

Stellantis had caused a stir this year when it introduced new contract language that would have forced suppliers to absorb more costs.

Among the new terms, which the company canceled this month, was a rule requiring North American suppliers to immediately pass on cost savings to Stellantis but prohibited them from charging higher prices when costs rise. Stellantis also had tried to give itself the ability to extend a supplier’s contract unilaterally.

After numerous complaints, Stellantis reverted to its 2021 terms in the region.

Horneck told suppliers in a letter announcing the reversal that Stellantis appreciated their input. The company “will work to continue to align with our supply base and aim for continued success for our respective organizations,” he wrote.

Vitous was selected as one of Automotive News’ 100 Leading Women in the North American Auto Industry in 2015, when she was director of product development purchasing for FCA US. She has been supply chain vice president since June 2019 and worked for the company since 1998, when was hired as a line supervisor at the Sterling Heights Assembly Plant in Michigan.

Shortly before Chrysler’s 2009 bankruptcy, she began working for purchasing boss John Campi as an executive planner.