Federal auto-safety regulators are opening an investigation into nearly one million General Motors pickup trucks and sport-utility vehicles after receiving hundreds of reports of engine failures. The National Highway Traffic Safety Administration said Friday it was launching the probe into vehicles equipped with a particular GM V-8 engine that had already been the subject of an earlier recall. The regulator has received nearly 500 complaints alleging engine failure in vehicles that had already been serviced under recall, including nearly two dozen that required complete engine replacements.

The regulator's newest probe covers nearly 998,000 vehicles, including model years 2021 to 2026 of the Cadillac Escalade and Chevrolet Silverado, two of GM's most profitable models.

GM stated: "The safety and satisfaction of our customers are the highest priorities for the entire GM team, and we continue to cooperate with NHTSA's evaluation of this matter."

This investigation raises concerns about the effectiveness of GM's previous recall efforts and could lead to additional safety mandates if the engine issues are found to be widespread.