US auto safety regulators announced Monday that they would hold a public hearing on whether Fiat Chrysler failed to fix defects in 20 recalls over the last two years.
Mark Rosekind, the administrator of the National Highway Traffic Safety Administration, said "significant questions have been raised" as to whether the automaker was meeting its obligations for recall repairs.
"It is not enough to identify defects. Manufacturers have to fix them," he said.
Representatives from the automaker will testify at a July 2 hearing on recalls carried out between 2013 and 2015. Other witnesses will include US safety regulators and consumers.
The NHTSA said in recent months it found problems with the "administration, execution and pace" of fixes to Fiat Chrysler vehicles.
Consumers have also complained of poor parts availability, difficulty obtaining appointments and "misinformation" from dealers, it said.
"Any auto defect that compromises the safety of our driving public is unacceptable," said Secretary of Transportation Anthony Foxx in a statement.
"Auto manufacturers are obligated to effectively remedy safety defects when they are discovered, and if they fail in that responsibility, we are obligated to act."
Possible penalties on Fiat Chrysler include requiring the automaker to buy back or replace vehicles, the agency said.
The agency also issued an order requiring Fiat Chrysler to provide documents related to the probe by June 1.