The US National Highway Traffic Safety Administration (NHTSA) has opened an investigation into the 2022 Hyundai Ioniq 5 for loss of motive power.

The auto safety regulator's Office of Defects Investigation (ODI) said it received 30 complaints from owners of 2022 Hyundai Ioniq 5 EVs, 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. 

The NHTSA said it opened a preliminary evaluation to assess the scope and severity of the potential safety defect, which is estimated to affect more than 39,500 Ioniq 5 EVs.

In a report published earlier this month, ODI said it learned from Hyundai that the failure is related to the ICCU (Integrated Control Charging Unit) that is responsible for powering both the HV (Hybrid Vehicle) battery and the LV (low voltage) 12-volt battery.

"Preliminary review indicates over-current within the ICCU (Integrated Control Charging Unit) can damage transistors (FET) in the LDC (DC-to-DC converter) resulting in the inability to recharge the 12V battery," read the report dated June 8.

A Hyundai spokesperson said in a statement to Automotive News that the automaker is "fully cooperating" with the investigation and will launch a service campaign in July.

"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. We value our cooperative relationship with NHTSA and have engaged in frequent, open and transparent dialogue with the agency on this topic."

Some of the customer complaints submitted to NHTSA suggest that this is a serious issue. One owner said his vehicle "became completely unresponsive" as he was using the Ioniq 5's ADAS traveling at 75 mph on a major highway. 

"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 January 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 seriously injured in a high speed crash."

Another owner wrote that their 2022 Ioniq 5 unexpectedly slowed to 20 mph after traveling at 40 mph and remained stuck at that speed.

"No matter how hard I pressed on the accelerator, it did not go over … 20 mph," they said of the February 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," the complainant added.

Fortunately, none of the incidents reported to ODI so far have been tied to any crashes or injuries. Once the NHTSA finishes the evaluation, it can either close the investigation or request the carmaker to issue a vehicle recall.

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