Why NHTSA Is Investigating Nearly 1 Million GM Trucks and SUVs for Engine Failure

Federal safety regulators have opened a new investigation into nearly one million General Motors trucks and SUVs after hundreds of owners reported their engines failed again, even after taking the vehicle in for a recall repair that was supposed to fix the problem. If your Chevrolet Silverado, GMC Yukon, or Cadillac Escalade sat through GM’s 2025 recall for this engine, the fix could well not have worked.

The National Highway Traffic Safety Administration said it opened the probe into 997,743 GM pickups and SUVs built for the 2021 through 2026 model years, all equipped with GM’s 6.2-liter L87 V8 engine. NHTSA’s Office of Defects Investigation received 499 complaints alleging engine failure in vehicles that had already gone through GM’s prior recall remedy. GM’s own internal complaint logs are far larger: the automaker has recorded 6,953 post-repair failure reports from its own customers.

What Is Actually Going Wrong Under the Hood

Owners describe three recurring symptoms: sudden loss of power while driving, severe engine knock, and complete engine shutdown. GM’s original 2025 recall, which still stands at 597,630 vehicles, attributed the underlying defect to a supplier part and rolled out a remedy meant to correct it. The new investigation exists for one reason: that remedy is not holding up in the real world for a meaningful share of owners.

NHTSA calls this a post-remedy failure analysis, a step above a standard preliminary evaluation. Investigators will examine whether GM’s original fix actually addresses the root cause of the L87 engine’s failures or whether it only delays the same breakdown. If the agency concludes the remedy is ineffective, it can force GM to issue a new, corrected recall covering some or all of the 997,743 vehicles now under review, a number that includes vehicles both inside and outside the original recall population.

Which Vehicles Are Covered

The investigation spans GM’s full-size truck and SUV lineup built with the L87 engine across the 2021 to 2026 model years, including the Chevrolet Silverado 1500, GMC Yukon, and Cadillac Escalade, along with related Suburban, Tahoe, and Sierra 1500 variants that share the same engine family. Owners can check whether their specific vehicle identification number is included in the original recall by entering it at nhtsa.gov/recalls, though a VIN that comes back clean under the 2025 recall does not rule out involvement in this newer investigation: NHTSA has not yet issued a formal recall expansion.

What Owners Should Do Right Now

Anyone driving one of these trucks or SUVs should watch for the same warning signs NHTSA is investigating: hesitation or a sudden drop in power under acceleration, a knocking sound from the engine bay that was not there before, or a stall while driving at speed. A vehicle that already went through the 2025 recall repair and is now showing these symptoms again should go back to a GM dealer immediately, and the owner should also file a complaint directly with NHTSA at nhtsa.gov/complaints or by calling the Vehicle Safety Hotline at 1-888-327-4236. Each additional complaint on file strengthens the evidence NHTSA uses to decide whether a new recall is necessary.

Owners whose vehicles have not yet been serviced under the original recall should not wait for the outcome of the new investigation. The existing recall repair remains free at any GM dealer regardless of how the post-remedy analysis concludes, and a car that has never been touched carries the highest risk of the failures NHTSA is now studying.

How This Fits Into GM’s Recall Record

The L87 engine has become one of the more persistent trouble spots in GM’s lineup. It powers the majority of the automaker’s current full-size trucks and SUVs, which means an engine-level defect touches an unusually broad slice of GM’s most profitable vehicles rather than a single niche model. GM has not disputed the complaint numbers NHTSA cited and has said it attributes the underlying defect to a supplier component, but it has not yet said whether it will move to a fresh recall ahead of NHTSA reaching a formal conclusion.

For buyers shopping the used market, a 2021-2026 Silverado, Yukon, Escalade, Suburban, Tahoe, or Sierra 1500 with the 6.2-liter L87 engine is worth a VIN check before purchase, along with a direct question to the seller about whether the recall repair was completed and when. A repair completed early in the recall’s rollout is more likely to be one of the units now generating complaints to NHTSA.

What Happens Next

NHTSA’s engineering analysis phase can run for months before the agency reaches a conclusion. Possible outcomes include a mandatory recall expansion covering additional repair work, a finding that the original fix is adequate and the complaints stem from unrelated causes, or a negotiated remedy between GM and NHTSA that falls short of a formal recall. Owners can track the investigation’s status by searching NHTSA’s investigation number for this campaign at nhtsa.gov/search-safety-issues, which the agency updates as the review progresses.

A Familiar Pattern for Post-Recall Failures

NHTSA opening a second-stage investigation into a remedy that already went through one recall cycle is not unusual, but it is a signal the agency treats seriously. Ford faced a similar sequence with earlier F-150 and Explorer camera and rearview issues, where an initial fix drew a follow-up wave of complaints that led to expanded coverage. Stellantis went through the same pattern this year with its own rearview camera recall covering more than 848,000 Chrysler, Jeep, and Ram vehicles, where owners kept reporting failures after the first repair round. When a post-remedy complaint count climbs into the thousands, as GM’s internal figure of 6,953 already has, agencies typically treat that as strong evidence the original fix undercorrected the defect rather than solved it.

For owners, the practical lesson from those earlier cases is not to assume a completed recall repair closes the book on a vehicle. Keeping the original recall paperwork and any post-repair service records makes it easier to document a repeat failure if NHTSA or GM eventually issues a second remedy. Owners with documented repeat failures are typically first in line for reimbursement if a new recall covers previously completed repairs.

Insurance and Warranty Considerations

An open NHTSA investigation does not by itself affect a vehicle’s insurability or resale value, but a confirmed defect that later becomes a recall can. Owners whose engines fail outside of a recall repair window should keep every repair invoice. GM’s standard powertrain warranty can cover part of the cost ahead of any NHTSA conclusion, and those records become critical if the automaker later agrees to reimburse out-of-pocket repairs as part of an expanded recall remedy.

Sources:

• Claims Journal: NHTSA Eyeing 1 Million GM Pickups, SUVs Over Engine Failure Concerns
• The Detroit News: Engine Failure Concerns Prompt NHTSA Probe of GM Pickups, SUVs
• NHTSA Recalls Database