Tarquini signed to drive for the FIRST team (again a former employer in F3000) and drove for them at the Formula One Indoor Trophy, but when their car failed crash tests he started 1989 without a ride. Following Philippe Streiff's career-ending pre-season testing crash, Tarquini joined Joachim Winkelhock in the AGS team from the second round of the series. There he finished a fine 8th on the road, being promoted to 6th after the exclusion of Thierry Boutsen and Alex Caffi. He was then one of the stars of the weekend in Monaco, threatening to qualify in the top 6 before ending up 13th on the grid. In the race he advanced to a strong 4th before being sidelined by an electrical problem. At the following Mexican Grand Prix he finished 6th, though the team's joy was tempered after Williams and Scuderia Italia successfully appealed against their Imola disqualification and Tarquini lost his point. More bad luck followed at Phoenix where Tarquini was holding 6th despite technical problems before Boutsen passed him on the final lap. At the wet Canadian Grand Prix Tarquini again ran well until being shoved off the track by René Arnoux (who eventually went on to finish 5th). The series then moved to faster tracks where the AGS was less competitive and the results of others meant Tarquini's entry (exempt for the first half of the season thanks to Streiff's efforts in 1988) would have to prequalify for the second half of the season.