"The occupant classification system for the front passenger-side airbag may malfunction, causing the passenger-side airbag to not operate as intended," NHTSA said in its problem description.
NHTSA said it has received 43 complaints about the alleged malfunction. There are no reports of crashes, injuries or fatalities linked to the probe.
"Many of the complaints note the malfunction occurred after the warranty period expired and mention high repair costs as a major deterrent to repairing the vehicle," NHTSA said.
The complaints report illumination of the airbag warning light.
"All of the complaints allege the cause of the light illumination to be a malfunction of the OCS sensor mat embedded in the passenger-seat cushion and/or report the presence of diagnostic trouble code B1448 which relates to the OCS sensor mat," NHTSA said.
The malfunction will cause the airbag diagnostic sensor to detect a fault in the airbag system.
The fault may result in the passenger-side airbag not being suppressed when a child or small adult is seated in the front-passenger seat or may disable the passenger airbag system when it is "occupied by a passenger that would otherwise require airbag protection," NHTSA said.
Federal safety regulators said they are opening a preliminary investigation to determine "the scope and severity of the potential problem and to fully assess the potential safety-related issues."
"KMA has already had substantial discussions with the National Highway Traffic Safety Administration (NHTSA) regarding the Occupant Classification System for certain 2007-'09 Spectra models and is cooperating with the agency in its investigation, said Kia in a statement. "KMA is not aware of any injuries resulting from this issue and supports NHTSA's recommendation that children remain in the back seat at least through age 12. "
Edmunds says: Owners of these cars will have to wait for federal safety regulators to finish their work before taking action. But if you have an immediate concern, it's best to contact your Kia dealer now.