The agency said there is a “strong correlation” between the loss of motive power and failure of the Integrated Control Charging Unit that powers the vehicle batteries.

NHTSA has opened a preliminary evaluation to assess the scope and severity of the potential safety defect, which could affect nearly 20,000 Kia EV6 electric compact crossovers.

A Kia spokesperson did not immediately respond to a request for comment.

The 2022 EV6 is the first dedicated EV that Kia has rolled out as part of its effort to debut eight EVs by 2029. This year through June, Kia has sold 8,328 of the electric compact crossovers, according to Automotive News data.

In one complaint submitted to NHTSA, a driver in Long Beach, Calif., reported hearing a loud pop from the rear passenger side of the vehicle followed by a warning light to check the vehicle’s charging system.

“All power to the vehicle was subsequently lost, immobilizing the vehicle,” the complainant said of the April 29 incident. “Dealer service department said ICCU board needs to be replaced but is on national backorder. Car has been immobilized since.”

Kia’s Korean sibling company Hyundai Motor Co. is dealing with a similar issue in the U.S.

Last month, NHTSA opened an investigation into more than 39,500 Hyundai Ioniq 5 EVs after receiving 30 complaints alleging loss of motive power. Many of the complaints also reported a “loud pop noise” followed by a warning displayed in the dashboard and reduced or total loss of motive power.

Hyundai spokesperson Michael Stewart said in June that the automaker is “fully cooperating” with the investigation.

“To address the concern, Hyundai is launching a service campaign in July that will update the affected vehicle’s software and replace the ICCU if necessary,” Stewart said in a statement. “We value our cooperative relationship with NHTSA and have engaged in frequent, open and transparent dialogue with the agency on this topic.”

Most NHTSA investigations start as preliminary evaluations, in which agency engineers request information from the manufacturer, including data on complaints, injuries and warranty claims. The manufacturer also can present its view regarding the alleged defect and may issue a recall.

After the evaluation, NHTSA will either close the investigation or move into the next phase. If a safety-related defect exists, according to NHTSA, the agency may send a “recall request” letter to the manufacturer.