The U.S. government’s highway safety agency is investigating complaints that engines could fail in as many as 1.4 million Honda and Acura vehicles.

The investigation by the National Highway Traffic Safety Administration covers the 2016 to 2020 Honda Pilot and Acura MDX, as well as the 2018 to 2020 Honda Odyssey and Acura TLX. The 2017 to 2019 Honda Ridgeline is also included.

The agency says in documents posted on its website Monday that connecting rod bearings in vehicles with 3.5-liter V6 engines can fail, leading to complete engine failure. Connecting rods connect the pistons to the crankshaft and convert vertical motion to move the wheels.

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Honda recalled approximately 250,000 vehicles in November 2023 to address the same issue. But the agency says it received 173 complaints from owners who reported rod bearing failures, but their vehicles were not included in the recall. A homeowner reported an accident with no injuries.

The agency said it is opening a recall petition to determine the severity of the problem in vehicles not included in the 2023 recall.

Honda said it would cooperate with NHTSA in the investigation.

In documents explaining the 2023 recall, the automaker said it had 1,450 warranty claims due to a bearing problem, but no reports of injuries. Dealers were required to inspect and repair or replace engines as necessary.