A federal engineering analysis opened on August 21 covers an estimated 1,164,820 General Motors, Honda and Acura vehicles whose electronic brake booster can fail, taking away braking assist and steering assist together. The National Highway Traffic Safety Administration, or NHTSA, has logged 745 complaints, 22 crashes or fires, six injuries and no deaths. No recall has been announced.
The probe is an upgrade of an inquiry NHTSA began in April 2024, and it is unusually broad. Its stated purpose is to assess the safety consequences of eBoost failures. The earlier inquiry, numbered PE24011, was a preliminary evaluation. It reaches past the GM models first examined to every vehicle that shares the part, including two Honda-badged electric SUVs that GM builds.
The eBoost module and what happens when it fails
The part at the center is GM’s eBoost, an electronic brake booster that replaces the vacuum booster of older cars. It multiplies the force of a driver’s foot on the pedal and feeds the stability and anti-lock systems. NHTSA’s Office of Defects Investigation describes the defect in its opening resume for EA26006 as an “electronic brake module component failure” that causes “loss of braking and steering assist functions.”
Owners’ descriptions are plainer. According to Motor1’s reading of the filing, drivers report “a hard brake pedal or a ‘Brake System Failure’ warning,” sometimes at startup and sometimes while moving. A hard pedal means the booster has stopped multiplying force, so the car still brakes but only for a driver pressing far harder than normal. The resume ties the same failure to loss of steering assist, which is why the central risk is two systems going at once. GM’s own account, laid out below, holds that this happens only after the vehicle has stopped, while some drivers describe something different and more abrupt, arriving while the car is still moving.
GM’s account and the complaints that contradict it
General Motors told NHTSA that the failure begins with a fractured spindle inside the booster. In the company’s words, as quoted by GM Authority, “the spindle fracture can cause the vehicle to lose ABS, brake assist, stability control, and traction control after the vehicle comes to a complete stop.” The car is then held to 43 mph.
That sequence is the benign version: the failure appears at a standstill, where a driver can decide not to leave. The agency’s resume says some complaints do not fit it. ODI notes that certain reports describe an immediate loss of brake assist during a braking event, not a delayed failure after the car has stopped, and the engineering analysis exists partly to find out how often that happens and why. A brake system that weakens at a stoplight is a nuisance; one that weakens during a hard stop at speed is a different kind of problem.
The count is ODI’s own: 745 complaints, 22 crashes or fires, six people hurt, none killed.
Which vehicles are in the population
The scope runs across three model-year bands. Model year 2023 through 2026 covers the Cadillac Lyriq, Chevrolet Colorado and GMC Canyon. Model year 2024 through 2026 covers the Buick Enclave and Envision, the Chevrolet Blazer EV, Equinox EV and Traverse, the Cruise Origin, the GMC Acadia, the Acura ZDX and the Honda Prologue. Model year 2025 and 2026 covers the Cadillac Celestiq and Optiq. In all, ODI counts 14 model lines across the three bands, spanning crossovers, pickups and electric SUVs.
Motor1 notes that the Honda Prologue and Acura ZDX share GM’s Ultium platform, which is how Honda and Acura owners came to appear in a probe centered on another company, even though the vehicles are sold under Honda and Acura badges. NHTSA’s recall lookup at its Check for Recalls page is where a VIN will show a campaign if one is ever issued.
What an engineering analysis can and cannot do
The legal weight of the step is easy to overstate. NHTSA’s own investigations page lists four kinds of defect investigation and gives a preliminary evaluation a target of eight months and an engineering analysis a target of 18 months. A recall can follow at either stage, and the difference in the target windows shows how much more work the agency expects from the deeper analysis.
ODI’s approvers signed off on the escalation: Kevin McGough is listed as investigator, Sharon Yukevich as reviewer and Tanya Topka as approver. The stated aim on the resume is to assess the safety consequences of eBoost failures across every GM vehicle that shares the system, so a final population could differ from the 1,164,820 now on file, either growing or shrinking as investigators learn which production runs carry the fracture-prone part.
Counting 18 months from the August 2026 opening puts the agency’s target for finishing at roughly February 2028, although GM could recall sooner and nothing obliges the agency to use the full period. The open question the filing leaves unanswered is the one that matters most to owners of these vehicles: how many of the 745 complaints describe an abrupt loss of brake assist while the car is moving, since ODI’s resume treats those reports as a reason the case moved past a preliminary look and into a formal analysis of the whole eBoost family across three brands. Motor1’s advice to owners who see a brake warning is to document each incident and contact a dealer instead of waiting for a recall notice.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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