In 1984, Gartner had secured the part-time second seat with the struggling Italian Osella team, as teammate to Piercarlo Ghinzani, driving a year-old, non-turbo FA1E. He qualified on his debut at the 1984 San Marino Grand Prix, but his race ended with an engine failure. At his next race, Gartner was given the new turbocharged Osella FA1F as the team decided to run a second car at all the remaining races. At the 1984 British Grand Prix, Gartner was allowed to start in 27th position because the Tyrrell Racing team was participating under appeal. However, his race ended when he was unable to avoid a first-lap accident involving Philippe Alliot and Eddie Cheever. After mechanical failures in the next two races, he finished 12th at the Dutch Grand Prix, five laps down on the winner Alain Prost.