General Motors (GM) has determined that certain 2018-2020 Buick Regal vehicles may have a software defect that could affect the power brake assist system. Because of this error, these vehicles fail to meet the Federal Motor Vehicle Safety Standards (FMVSS) for “Braking Systems”.
In April 2022, a brake performance issue on a 2019 Opel Insignia, a sister vehicle of the Buick Regal, was brought to the attention of GM’s Speak Up For Safety (SUFS) program. An investigation was opened and the problem was found to be a software issue. According to the defect report, a software error could cause the hydraulic brake boost to fail and not respond to a loss of brake vacuum pressure. Tests conducted on a Buick Regal by GM, showed that stopping distance following the loss of vacuum brake pressure could exceed FMVSS 135 requirements by 1-5 percent.
Field data has identified four claims received by GM in which the vehicle’s invalid vacuum pressure diagnostic trouble code (DTC) was set and the hydraulic brake boost was disabled. None of these claims involved an allegation that the condition contributed to a crash, and GM is not aware of any crashes or injuries relating to this condition. In June, GM’s Safety Field Action Decision Authority (SFADA) decided to conduct a non-compliance recall.
According to the defect report, a loss of vacuum brake assist pressure will cause these vehicles to exceed the stopping distance requirements. If the vehicle’s vacuum-power brake assist partially or fully fails, braking events may require additional stopping distance, depending on the brake pedal force applied by the driver. Increased stopping distances could increase the risk of a crash.
NOTE: During a partial or full loss of vacuum brake assist, the vehicle may display a message in the Driver Information Center, a malfunction warning light may illuminate and the driver may notice increased brake pedal resistance.
Owners receiving notices will be asked to return to their dealers to have the EBCM software updated in their vehicles. The NHTSA campaign number for this recall is 22V-465.