A judge in Turin, Italy, on Wednesday dismissed a lawsuit from the daughter of Fiat SpA patriarch Gianni Agnelli that had challenged the valuation of his estate and could have placed a previous agreement regarding control of Fiat in doubt.

Margherita Agnelli de Pahlen had asked three of her father's advisers for a full accounting of the late Mr. Agnelli's wealth, according to a court filing. Margherita Agnelli's mother, Marella Agnelli, was also named in the suit.