More than 1.1 million GM vehicles are now under a broader investigation after drivers reported losing brake assist, including several EVs and models built for Honda.
GM vehicles under investigation by the ODI
The National Highway Traffic Safety Administration (NHTSA) expanded its investigation on Monday as the agency continues to receive complaints related to the issue.
On April 11, 2026, the agency’s Office of Defects Investigation (ODI) opened a preliminary evaluation after receiving multiple complaints about a loss of brake assist in 2023 Cadillac Lyriq models.
After pressing the brake pedal hard, drivers said a “Brake System Failure” message popped up while starting or driving the vehicle.
GM said the issue was due to alleged spindle fractures in the eBoost system. In records shared with the ODI, GM said that when this happens, the anti-lock brakes (ABS), stability control, and traction control remain functional until the vehicle stops. Once fully stopped, these functions are lost.
The loss of function triggers three Diagnostic Trouble Codes (DTCs) that activate the driver alerts, including “Service Brake System.”
Since opening the preliminary evaluation in April, the ODI said it has “continued to receive reports of loss of brake assist.”
The ODI added that the reports “allege an immediate loss of brake assist functionality as opposed to the loss occurring after the vehicle comes to a complete stop,” as GM indicated.
As a result, ODI is moving it to an “engineering analysis” and expanding the scope of the investigation to include all GM vehicles with the eBoost system.
The vehicles under investigation include: 2023-2026 MY Cadillac Lyriq, Chevrolet Colorado, and GMC Canyon; 2024-2026 MY Buick Enclave, Envision; Chevrolet Blazer EV, Equinox EV, Traverse; Cruise Origin; and GMC Acadia; 2025-2026 MY Cadillac Celestiq and Optiq.
The engineering analysis also includes 2024-2026 MY Acura ZDX and 2024-2026 MY Honda Prologue vehicles that were equipped with GM’s eBoost system.
According to ODI’s report, the issue has resulted in 745 incidents, including 22 crashes/fires, five of which caused injuries. The agency estimates that 1,164,820 GM vehicles are potentially impacted.
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