Herbert Diess, the Volkswagen CEO whose image had been tarnished in the fallout from the German auto maker’s emissions-cheating scandal, is stepping down.

In a surprise announcement on Friday, the Wolfsburg, Germany-based company said Diess will depart September 1 “by mutual consent” with the board. No reason was given for his departure. Oliver Blume, CEO of VW brand Porsche, will succeed Diess.

Diess, who took over as chief executive in 2018, presided over the automaker at a time of significant change in the industry, including a shift toward increased production of electric vehicles. His contract was set to expire in 2025.

Board chairman Hans Dieter Poetsch thanked Diess in a statement and praised his role in “advancing the transformation of the company”.

“Not only did he steer the company through extremely turbulent waters, but he also implemented a fundamentally new strategy,” Poetsch said.

Diess focused on Volkswagen’s shift toward zero-emissions vehicles, but analysts say he wasn’t able to create change within the company and that the carmaker has fallen behind in some key developments such as software implementation.

“With industry challenges accelerating and a growing number of new and fast-follower challengers, the new management offers an opportunity to revisit strategy or jump-start stalled relationships,” analysts at Jefferies Equity Research said in a research note.

Shortly before his ouster was announced, Diess posted on LinkedIn about the difficulties facing the auto maker — from Russia’s war in Ukraine to a shortage of computer chips that has stymied production.

Despite those struggles, he said he was “very satisfied with our performance”, citing high demand for Volkswagen’s electric vehicles and a rebound in China after Covid-19 lockdowns.

“After a really stressful first half of 2022 many of us are looking forward to a well-deserved summer break,” his post said.

Diess reportedly has clashed with the company’s powerful labour representatives over issues including top personnel decisions. Workers hold an unusual amount of clout at Volkswagen.