NHTSA Office of Defects Investigation
Preliminary Evaluation PE24-015: Rear-end Collisions Involving Zoox Vehicles
- Closed
NHTSA's Office of Defects Investigation opened Preliminary Evaluation PE24-015 on May 10, 2024 and closed it on March 31, 2025. NHTSA's investigations file lists the Zoox Zoox Robotaxi and Automated Driving System for it and links recall 25E-019 to it.
Updated daily from NHTSA's investigations file
Key facts
- NHTSA number
- PE24-015 (also written PE24015)
- Investigation type
- Preliminary Evaluation The first stage of most defect investigations: NHTSA's Office of Defects Investigation gathers basic information about a possible safety defect, including from the manufacturer.
- Status
- Closed March 31, 2025
- Opened
- Closed
- Vehicle or equipment manufacturer
- Zoox, Inc.
- Components
- Electrical System — ADAS — Autonomous/Self Driving; Electrical System — ADAS — Autonomous/Self Driving — Software
- Recall linked by NHTSA
- 25E-019 (NHTSA record)
- Vehicles and equipment
- Zoox Zoox Robotaxi and Automated Driving System
NHTSA's summary
As NHTSA's Office of Defects Investigation wrote it for Preliminary Evaluation PE24-015.
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 Preliminary Evaluation. NHTSA reserves the right to take additional action if warranted by new circumstances. To review the SGO reports cited above, go to NHTSA.gov/laws-regulations/standing-general-order-crash-reporting. The SGO report ID numbers are provided below: 30610-7578 30610-7589 30610-4810
Vehicles and equipment listed for this investigation
NHTSA's investigations file lists these vehicles and equipment for Preliminary Evaluation PE24-015. A listed model year means only that an investigation names it; it says nothing about any particular vehicle. Model years with a try.vin recall page link to that page's NHTSA investigations section.
Zoox
All Zoox recallsWhat an NHTSA investigation is
NHTSA's Office of Defects Investigation (ODI) looks into possible safety defects in vehicles and equipment, often after owner complaints. An investigation usually starts as a Preliminary Evaluation, or as a Recall Query when it concerns whether an existing recall covers the right vehicles or fixes the problem, and ODI can upgrade it to a more detailed Engineering Analysis. A Defect Petition asks NHTSA to open an investigation, and Audit and Equipment Queries are administrative investigations into whether companies complied with federal vehicle safety requirements, such as reporting, recall and certification rules.
An open investigation is not a finding that a safety defect exists, and NHTSA can close one without a recall.
To see whether a specific vehicle has an open recall, enter its VIN at nhtsa.gov/recalls.
Free VIN check: decode a VIN to see its year, make and model.
Sources
NHTSA's investigation record for PE24-015
Investigation details come from NHTSA's investigations file, which try.vin imports once a day. The investigation types are described from the U.S. Department of Transportation Inspector General's May 2023 report on NHTSA's Office of Defects Investigation, NHTSA's petition rules (49 CFR Parts 552 and 557) and NHTSA's Office of Defects Investigation procedures. How try.vin reads NHTSA investigations.