NHTSA is investigating complaints of steering problems and frame weld deficiencies in some 2018 and 2019 Jeep Wranglers.
The investigation covers an estimated 270,000 vehicles, a NHTSA spokesperson told Automotive News in an email.
The agency lists more than 3,500 consumer complaints about steering or frame weld concerns in its investigation documents.
A citizen petitioned NHTSA to start an investigation in October 2018, documents said. The petition featured a list of complaints including "porous welds, excessive slag, lack of weld penetration, over penetration of welds, overweld or weld drip, and weld splash ... allegedly located at a variety of locations on the frame assembly."
Fiat Chrysler Automobiles recalled 18,055 Jeep Wranglers in September 2018 over steering problems related to a front bar bracket with an "out-of-specification weld," which might result in the bracket separating from the frame.
No crashes, injuries or deaths have been reported in connection to the current investigation, NHTSA documents said.
A spokesman for FCA told Automotive News the company is cooperating with the investigation.
Sales of the Jeep Wrangler where down 12 percent to 116,985 through the first six months of the year, according to the Automotive News Data Center. FCA now reports sales on a quarterly basis.