The U.S. National Highway Traffic Safety Administration (NHTSA) has expanded its investigation into reports of lost brake assist to include approximately 1,164,820 vehicles equipped with General Motors’ eBoost system, including several electric models and vehicles manufactured by GM for Honda. The move follows the continued receipt of new reports since the preliminary evaluation was opened in April 2026.
NHTSA’s Office of Defects Investigation (ODI) began a preliminary evaluation on April 11 focused on 2023 Cadillac Lyriq models, after drivers reported that a “Brake System Failure” message appeared when pressing the brake pedal firmly or while driving. However, the office said subsequent reports described an immediate loss of brake-assist function, rather than the problem occurring after the vehicle had come to a complete stop, a significant difference from the description GM provided in its records to the regulator.
Which Models Are Included?
The engineering analysis covers vehicles from model years 2023 through 2026, including the Cadillac Lyriq, Chevrolet Colorado, and GMC Canyon. It also includes the Buick Enclave and Envision, the Chevrolet Blazer EV, Equinox EV, and Traverse, as well as the Cruise Origin and GMC Acadia. The list also includes the Cadillac Celestiq and Optiq from model years 2025 and 2026.
The investigation is not limited to GM brands; it also includes the Acura ZDX and Honda Prologue from model years 2024 through 2026 when these vehicles are equipped with the eBoost system supplied by GM.
What Do the Available Data Show?
According to the ODI report, the issue has so far been associated with 745 incidents, including 22 crashes or fires, and five of these incidents resulted in injuries. GM said the alleged cause involves fractures in a shaft inside the eBoost system. According to records the company shared with ODI, the anti-lock braking systems (ABS), stability control, and traction control remain operational until the vehicle comes to a complete stop, after which these functions lose effectiveness.
The condition activates three diagnostic trouble codes, along with warnings to the driver, including “Service Brake System.” However, the case’s move to the “engineering analysis” stage means that NHTSA is continuing to examine the scope, cause, and consequences of the problem; it does not by itself represent a final declaration that a defect exists or a decision to conduct a recall.
Why Does This Investigation Matter?
The significance of the development lies in its broad scope and its inclusion of electric and conventional vehicles sold under different brands, making it more important to identify the source of a fault in a shared system than to address a single model. The difference between losing assistance when stopped and losing it immediately while driving could also change the assessment of the risk level and how the driver responds.
At present, the text does not specify repair procedures or a recall campaign, nor does it clarify whether all of the vehicles covered actually experience the problem. Therefore, the investigation’s final findings and any guidance issued by NHTSA or the companies concerned remain open for review.