Investigations
Rear-end Collisions Involving Zoox Vehicles
NHTSA Preliminary Evaluation PE24015 — closed, opened 2024-05-10.
NHTSA investigation PE24015 is a Preliminary Evaluation opened on 2024-05-10 and currently closed. The subject is tracked inside the Office of Defects Investigation queue. Latest activity on this investigation was logged on 2025-03-31 — NHTSA updates that field whenever an Information Request goes out, a supplement is filed, or a status change is recorded in the public docket.
A Preliminary Evaluation like PE24015 is the entry point of the federal defect-investigation process. NHTSA engineers scan complaint databases, field reports, and manufacturer data to decide whether an Engineering Analysis is warranted, whether a voluntary recall is already sufficient, or whether the pattern does not rise to a defect finding.
Investigators summarized the matter as follows: "On May 10, 2024, the Office of Defects Investigation (ODI) opened a Preliminary Evaluation (PE24015) to assess reports of sudden unexpected braking in Zoox vehicles, leading to rear-end collisions, as well as to evaluate t..." Investigations are the early-warning layer of the federal auto-safety system, sitting upstream of formal recalls and defect orders. Whether this one closes without action or escalates into an Engineering Analysis, the full history stays in the ODI archive so researchers, litigators, and buyers can pull the paper trail at any time.
Investigation Summary
On May 10, 2024, the Office of Defects Investigation (ODI) opened a Preliminary Evaluation (PE24015) to assess reports of sudden unexpected braking in Zoox vehicles, leading to rear-end collisions, as well as to evaluate the performance of the Zoox Automated Driving System in crosswalks around vulnerable road users and in other similar rear-end collision scenarios. These unexpected braking events can increase the risk of a collision. To assess these risks, ODI collected information from Zoox as part of this investigation. In response to ODI’s Request for Information, Zoox provided information describing hard braking events commanded by the ADS. These hard braking events were identified by certain thresholds, including rate of deceleration. ODI analyzed the hard braking events commanded by the Zoox ADS and determined that Zoox ADS-equipped vehicles contributed to 4 collisions. Each of these collisions involved a vulnerable road user, with three of the incidents resulting in injury. Three of the collisions were reported under Standing General Order 2021-01 (SGO), while the other collision was not reportable under the SGO. On March 13, 2025, Zoox filed a safety recall (NHTSA Recall No. 25E019) stating that in specific circumstances “the Zoox ADS software may have reacted over-cautiously and braked unnecessarily hard” and that “the Zoox ADS software may have incorrectly anticipated a collision and braked unnecessarily hard.” These behaviors could lead to increased risk of a rear-end collision caused by unnecessary hard braking. The Zoox recall report indicated that Zoox's ADS has been remedied through a software update that addresses the described defects. As of November 7, 2024, the updated software was released to all impacted Zoox vehicles. In view of the recall action taken by Zoox and ODI’s analysis of the available data, including data presented by Zoox demonstrating a resolution of these hard braking incidents after the software update, ODI is closing this Prelimina
About This Investigation Type
A Preliminary Evaluation (PE) is the first phase of NHTSA's investigation process. It is opened when the agency identifies a potential safety defect pattern, usually triggered by consumer complaints, manufacturer reports, or field monitoring. During a PE, NHTSA gathers information to determine whether a formal engineering analysis is warranted.
Data from NHTSA Office of Defects Investigation. Cross-references: NHTSA recall campaign API and NHTSA FARS where fatality records overlap. PlainCars does not rate or recommend vehicles. Learn more.
Read our methodology — how this data is sourced, computed, and verified.