NHTSA Expands Investigations into General Motors Brake-Assist System and 6.2-L V8 Engine

In late August 2026 the National Highway Traffic Safety Administration (NHTSA) opened two engineering analyses that broaden earlier inquiries into General Motors Co. vehicles. The first targets the eBoost brake-assist system used on more than 1 million GM trucks, SUVs and electric models after additional complaints of sudden loss of brake assist. The second examines the 6.2-liter L87 V8 engine installed in nearly one million full-size GM trucks and SUVs, following post-recall failure reports. Both probes remain in the data-gathering stage and could lead to expanded recalls.

US Safety Regulators Escalate Probe Into 6.2L V8 GM Trucks After Reports of Post-Recall Engine Failures GM’s V8 engine under renewed scrutiny by the NHTSA Detroit NewsElectrekGM 6.2-Liter L87 V8 Under NHTSA Investigation After Recall Fix Fails Even The Feds Are Fed-Up With GM's Excessive V8 Engine Failures

The eBoost system, first deployed in the 2023 Cadillac Lyriq, combines regenerative braking with hydraulic brakes. In April 2026 NHTSA’s Office of Defects Investigation (ODI) opened a preliminary evaluation after owners reported loss of brake assist. GM attributed the problem to spindle fractures in the eBoost assembly and said anti-lock brakes, stability control and traction control remain functional until the vehicle stops.

Detroit NewsElectrekGM 6.2-Liter L87 V8 Under NHTSA Investigation After Recall Fix Fails GM’s V8 engine under renewed scrutiny by the NHTSA US Safety Regulators Escalate Probe Into 6.2L V8 GM Trucks After Reports of Post-Recall Engine Failures Even The Feds Are Fed-Up With GM's Excessive V8 Engine Failures

The L87 6.2-L V8 engine was subject to a voluntary recall (Recall 25V-274) in 2025 that addressed machining flaws in crankshafts, connecting rods and oil passages. The remedy offered a full engine replacement or a service upgrade that switched oil viscosity from 0W-20 to 0W-40 and replaced the oil filter and cap.

GM’s V8 engine under renewed scrutiny by the NHTSA

• Brake-assist investigation – The ODI’s expanded analysis now covers an estimated 1,164,820 GM vehicles equipped with eBoost. The agency has logged 745 incidents, including 22 crashes or fires and 5 injuries.

Electrek

• Engine investigation – The analysis encompasses 997,743 trucks and SUVs from model years 2021-2026. NHTSA records 499 complaints of engine failure after the 2025 recall, with 473 linked to the oil-viscosity remedy and 26 to full-engine replacements. An additional 191 reports involve vehicles built after the May 31 2024 cutoff, bringing the total of new failure reports to 690. GM’s data show 6,953 post-remedy failure complaints, consolidated to 6,050 distinct claims after duplicate removal. The ODI file notes 12 crashes and 12 minor injuries tied to the L87 failures.

US Safety Regulators Escalate Probe Into 6.2L V8 GM Trucks After Reports of Post-Recall Engine Failures

NHTSA described the engineering analysis as a formal technical evaluation of components, test protocols and supplier controls.

GM 6.2-Liter L87 V8 Under NHTSA Investigation After Recall Fix Fails

• Brake-assist loss – NHTSA documents allege an “immediate loss of brake assist” during braking, whereas GM’s filing states the loss occurs only after the vehicle comes to a complete stop.

Detroit News

• Failure counts – The brake-assist investigation cites 745 incidents, while a Detroit News article does not provide a total figure, leaving the overall tally partially unverified.

Detroit News

• Engine-failure data – NHTSA reports 499 post-recall complaints, whereas GM’s internal logs record 6,953 such complaints. The agency has not clarified whether the higher GM figure includes duplicates or unrelated reports.

US Safety Regulators Escalate Probe Into 6.2L V8 GM Trucks After Reports of Post-Recall Engine Failures

• Outcome uncertainty – Both investigations are ongoing; no recall decisions have been announced, and timelines for final determinations remain undisclosed.

GM 6.2-Liter L87 V8 Under NHTSA Investigation After Recall Fix Fails

NHTSA will complete its analyses and decide whether the evidence warrants an expanded recall for the eBoost system or the L87 engine. GM has pledged to continue cooperating and to honor the existing 10-year/150,000-mile coverage program for affected vehicles. Owners should retain service records, monitor for warning lights or unusual performance, and report any issues promptly to their dealers or to NHTSA.

GM 6.2-Liter L87 V8 Under NHTSA Investigation After Recall Fix Fails