The U.S. National Highway Traffic Safety Administration said Friday it has strengthened and broadened an investigation into approximately 1 million General Motors (GM.N), opens new tab trucks and sport utility vehicles over a problem involving engine failure that resulted in a recall in 2025.

The agency said it was conducting an engineering analysis. This is a higher level of inquiry than a formal review it began earlier this year to see whether the repair made by the company worked.

Before an agency can attempt to force an expanded recall, it must conduct an engineering analysis.

The subject vehicles are Cadillac Escalade, Chevrolet Silverado 1500, Suburban, Tahoe, GMC Yukon and Sierra 1500 equipped with L87 engines for the 2021-2026 model years.

In 2025 GM recalled almost 600,000 2021-2024 model year vehicles citing problems from its supplier over quality issues but which caused engine failure. The failures occurred while driving in some cases.

Nearly 7,000 owners of vehicles that have had work done in regard to the recall claimed engine failure; NHTSA has 499 similar claims.

In vehicles with L87 engines but which were not part of the recall, the NHTSA has 191 such claims of failure, the agency said.

The remedy on the recall was to examine the engine and perhaps replace it and also possibly change part of the oil system.

GM stated that it will continue working with NHTSA while it evaluates the recall and claimed it already had initiated three investigations on the problem in 2022-2024 and issued a recall after a NHTSA inquiry initiated last year.

The data identified slightly more than 28,000 complaints during GM's 2024 investigation; of that number roughly half alleged lost propulsion of the vehicles.

GM disclosed in 2025 that 12 accidents and 12 injuries likely were associated with the issue in the U.S.; an additional 42 fires may have been linked to it as well, however all the stated injuries were slight.

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Tanu