WASHINGTON — The nation’s top auto safety regulator has opened an investigation into the 2022 Hyundai Ioniq 5 after receiving more than two dozen consumer complaints alleging loss of motive power in the electric compact crossover.

NHTSA’s Office of Defects Investigation said it received 30 complaints about the problem from U.S. vehicle owners, many of which reported a “loud pop noise followed by a warning displayed in their dashboard” and immediately experienced a reduced or total loss of motive power.

NHTSA has opened a preliminary evaluation to assess the scope and severity of the potential safety defect, which could affect more than 39,500 Ioniq 5 EVs.

In a report made public this month, Hyundai told NHTSA investigators that the issue is related to the Integrated Control Charging Unit that powers the vehicle batteries. An initial review indicated that overcurrent within the charging unit can damage transistors, preventing the 12-volt battery from recharging, the report stated.

Hyundai spokesperson Michael Stewart said 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.”

The Ioniq 5 is the first dedicated electric offering from Hyundai, replacing the now discontinued Ioniq EV in the lineup. This year through May, Hyundai has sold more than 10,500 of the popular compact crossover, according to Automotive News data.

In one complaint submitted to NHTSA, the vehicle unexpectedly slowed to 20 mph after traveling at 40 mph.

“No matter how hard I pressed on the accelerator, it did not go over … 20 mph,” the complainant said of the Feb. 3 incident. “The dashboard also said speed limited to 20 mph. I had to pull over on the side of the road. Turn off the ignition. Then turned it back on. Then the car resumed to operate as normal. Luckily there were no other cars around so I could safely pull over.”

Another report involved a driver who was using the vehicle’s advanced driver-assistance system and traveling at 75 mph on a major highway when the vehicle “became completely unresponsive.”

“The car stopped accelerating, and I was unable to resume driving. I was forced to coast to a stop on the side of the highway,” the complainant said of the Jan. 18 incident. “I had my daughter with me and were I not able to safely maneuver between the semi trucks, we could have been killed or seriosuly [sic] injured in a high speed crash.”

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.