Law & Order

NHTSA Issues Finalized Rule on Automatic Emergency Braking

Automatic Emergency Braking

By the SEMA Washington, D.C., office

The National Highway Traffic Safety Administration (NHTSA) has finalized a Federal Motor Vehicle Safety Standard, FMVSS127, that makes automatic emergency braking (AEB), including pedestrian AEB, standard on all passenger cars and light trucks weighing up to 10,000 lbs. by September 2029.  

According to NHTSA, "The new standard requires all cars be able to stop and avoid contact with a vehicle in front of them up to 62 miles per hour and that the systems must detect pedestrians in both daylight and darkness. In addition, the standard requires that the system apply the brakes automatically up to 90 mph when a collision with a lead vehicle is imminent, and up to 45 mph when a pedestrian is detected." Under the rule, vehicles will be required to have an AEB system that applies the brakes automatically at any forward speed greater than 6.2 mph when a collision with a lead vehicle or a pedestrian is imminent.

SEMA provided extensive comments to NHTSA in response to the agency's proposed rulemaking in August 2023. The finalized rule includes a SEMA-specific section focused on aftermarket modifications and references SEMA members (alterers) and repair businesses.  

Although the final rulemaking focuses on vehicle manufacturers, NHTSA concluded that alterers and repair businesses are obligated to prevent a noncompliance with FMVSS 127 created by this final rule. The rule provides some flexibility in terms of compliance for law enforcement vehicles.

Other significant elements of the new federal safety standard for AEB include:

  • Deactivation of AEB will not be permitted, except in very limited law enforcement circumstances. 
  • Adoption of the full collision avoidance (e.g. no contact), which requires the subject vehicles to not make contact with the lead vehicle in all AEB performance tests listed in the regulation.

The final rule did not adopt SEMA's recommendation that the rule should require automakers to share specific information, such as diagnostic codes, with consumers. 

SEMA Garage and Government Affairs staff are reviewing the final rule to better understand how it will impact our members. Once that review is complete, SEMA will be in contact with its membership to explain the details of the rule and the impact it will have on their businesses.

In the meantime, those who may be affected by this ruling or have questions may contact

A link to the NHTSA announcement and full rule can be found here: NHTSA Finalizes Rule on Automatic Emergency Braking.