Investigations
6L90 Transmission Failure
NHTSA Preliminary Evaluation PE23016 — closed, opened 2023-09-27.
NHTSA investigation PE23016 is a Preliminary Evaluation opened on 2023-09-27 and currently closed. The subject is tracked inside the Office of Defects Investigation queue. Latest activity on this investigation was logged on 2025-01-10 — 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 PE23016 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: "The Office of Defects Investigation (ODI) opened this Preliminary Evaluation (PE) after receiving one Vehicle Owner Questionnaire (VOQ) complaint related to four school buses built on General Motors (GM) van chassis. The..." 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
The Office of Defects Investigation (ODI) opened this Preliminary Evaluation (PE) after receiving one Vehicle Owner Questionnaire (VOQ) complaint related to four school buses built on General Motors (GM) van chassis. The VOQ alleged transmission failure resulting in a loss of all forward gear. In ODI's pre-investigative discussions with GM, ODI learned that valve body separator plates had been machined out of tolerance during production periods between October 2016 to April 2017 and February 2021 to April 2021. This out of tolerance machining may create excessive wear to the valve body check balls, possibly resulting in an inability to engage drive or reverse. The potential loss of drivability only begins when shifting from a park or neutral transmission selection and does not occur during a functional drive cycle. The average failure mileage of vehicles which experienced this condition is within warranty and related claims or complaints did not include any accidents, injuries, or fatalities. After discussions with GM, Technical Service Bulletin (TSB) 23-NA-142 (NHTSA ID number 10243753) was released in September 2023. This technical service bulletin provides a procedure for technicians to replace the forward check ball and separator plate if found to be the cause of a customer's concern. During the course of the investigation, GM also released a Customer Satisfaction Program (CSP) N232428780 (NHTSA ID 10253316) in February 2024, to notify school bus and ambulance fleets of the concern and to proactively mitigate the risk in these essential-operation vehicles. Recently, ODI contacted multiple school bus fleets, verifying that there have not been any stranded buses mid-route from this condition. Additionally, ODI has not received any additional VOQ complaints since the opening of this investigation. Based on the available information, including GM's TSB and CSP, this PE is closed. The closing of this investigation does not constitute a finding by NHTSA that a safety-
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.