The Winterthur-based company issued a statement on Wednesday acknowledging that its German unit had been targeted by the German Federal Cartel Office.
The German competition watchdog said it has carried out searches at the parts makers.
It suspects the groups — which it did not name — of being involved in illegal price-fixing for car boot fittings and carpeting since 2002.
Canadian group Magna said in a separate statement that it was one of the companies targeted in the raids.
Both Autoneum and Magna said they would cooperate with the German authorities.
Autoneum could not comment on the specific allegations but it cited its code of conduct, which requires units to comply with all applicable laws, “including antitrust and competition regulations”.
The searches were conducted in the states of Baden-Wuerttemberg, Hesse, Lower Saxony, North Rhine-Westphalia and Bavaria.
The Autoneum Group describes itself as a “global technology leader in acoustic and thermal management solutions for motor vehicles”.
With customers that include all the major automakers, the group operates plants in 20 countries.