Federal regulators have escalated their investigation into General Motors' 6.2-liter L87 V8 engine to a formal Engineering Analysis, pulling nearly one million pickup trucks and SUVs into a probe that now questions whether the automaker's 2025 recall fix actually worked. The National Highway Traffic Safety Administration opened the expanded inquiry, designated EA26005, on Thursday, covering 997,743 model year 2021-2026 vehicles equipped with the engine.
The Engineering Analysis marks the agency's final investigative stage before it can request or order a safety recall, according to AutoGuide. As The Detroit News reported, NHTSA has received 499 complaints alleging engine failures in vehicles that had already undergone GM's earlier recall remedy, prompting the agency to say it will continue investigating those post-recall failures and assess whether GM's fixes were effective.
A Recall That May Not Have Reached the Root Problem
GM's original recall, filed with regulators as 25V-274 in April 2025, covered roughly 600,000 vehicles built between March 1, 2021, and May 31, 2024. In that federal filing, the automaker disclosed it had received 28,102 U.S. field complaints or engine-failure incidents tied to the L87 unit, per the NHTSA Part 573 Safety Recall Report.
GM attributed the failures to a third-party supplier, according to the seed reporting, and its federal filings pointed to two specific manufacturing defects: machining sediment left behind on connecting rods and inside crankshaft oil galleries, plus crankshafts that were out of spec on dimensions and surface finish. Metal debris circulating through those oil galleries degrades bearings and can cause a sudden loss of propulsion, the recall report notes.
The fix itself varied depending on how a vehicle tested. Trucks and SUVs that failed a dealer acoustic inspection got full engine replacements, though the AutoGuide report notes that parts backorders caused widespread delays. But vehicles that passed that acoustic test received only an oil change, switching to heavier Mobil 1 FS 0W-40 along with a new oil fill cap, a remedy AutoGuide reports was criticized for failing to flush out metal debris already circulating inside the engine.
Newer Trucks Now Swept Into the Probe
What has changed since last year is the scope. NHTSA has now logged 191 reports of catastrophic engine failures in GM vehicles built after May 31, 2024 — outside the window GM's original recall ever covered, according to AutoGuide. That statistic is a central reason the 2025 and 2026 model years were pulled into the investigation for the first time.
The expanded probe spans seven GM truck and SUV nameplates, including the Chevrolet Silverado 1500, Chevrolet Suburban, Chevrolet Tahoe, GMC Sierra 1500, GMC Yukon, GMC Yukon XL, Cadillac Escalade and Cadillac Escalade ESV, per the seed reporting and AutoGuide's rundown of affected models. Those full-size trucks and large SUVs represent some of GM's highest-margin vehicles in North America, AutoGuide notes.
How Regulators Got Here
The path to Thursday's Engineering Analysis wasn't sudden. Federal recall documentation shows GM closed three separate internal product investigations into L87 engine failures — in February 2022, June 2023 and July 2024 — before opening a formal internal investigation in January 2025 after NHTSA notified the company, according to the recall report. GM has stated that earlier field data did not initially show a clear safety defect trend.
Before escalating to an Engineering Analysis, NHTSA opened a preliminary Recall Query, designated RQ26001, in January of this year specifically to evaluate whether the oil-change remedy was actually preventing engine destruction, AutoGuide reports. A Recall Query is typically opened when regulators suspect an earlier recall fix failed to eliminate the hazard it was meant to address.
What an Expanded Recall Could Mean for GM
The stakes for GM are considerable. Under the National Traffic and Motor Vehicle Safety Act, an Engineering Analysis lets federal engineers demand extensive internal engineering data, and that authority can ultimately compel an automaker to conduct a redesigned or expanded safety recall, according to Finimize. Finimize notes that a mandated expansion would force GM to set aside additional warranty reserves and provide hardware remedies rather than the oil-change fix used previously.
The vehicles under scrutiny sit at the center of GM's truck business at a moment when the company has been investing heavily in its V8 manufacturing footprint. In May 2025, amid mounting reliability scrutiny over its V8 powertrains, GM announced an $888 million investment to modernize its Tonawanda Propulsion Plant in New York for next-generation V8 engine production, a project that drew up to $16.96 million in state tax credits from Empire State Development, as per Hoodline.
For now, the size of the fleet under review — nearly a million trucks and SUVs spanning GM's Chevrolet, GMC and Cadillac brands — means the outcome of NHTSA's Engineering Analysis carries real financial exposure for the automaker's most profitable vehicle lines. The agency has said it will continue investigating the post-recall failures and evaluate whether GM's remedies actually worked, but has not yet determined whether a broader recall will be required.
