Published March 1, 2026
NHTSA Investigations: How the Government Decides to Investigate
When NHTSA opens an investigation into a potential vehicle defect, it triggers a structured process that can result in a recall affecting millions of vehicles. Understanding how NHTSA decides which complaints to investigate, how investigations progress, and what powers the agency has helps consumers appreciate the role their complaints play in vehicle safety.
The Office of Defects Investigation
NHTSA's Office of Defects Investigation (ODI) is responsible for identifying and investigating potential safety defects in motor vehicles and motor vehicle equipment. ODI reviews thousands of consumer complaints, manufacturer reports, and field data each year to determine whether defect patterns exist that warrant formal investigation.
Phase 1: Screening
ODI continuously screens incoming data from multiple sources including consumer complaints, manufacturer Early Warning Reports (required by the TREAD Act), insurance and crash data, media reports and social media trends, and foreign recall notifications. When a pattern emerges that suggests a potential safety defect, ODI may advance to a formal investigation.
Phase 2: Preliminary Evaluation
A Preliminary Evaluation (PE) is the first formal investigation step. During a PE, ODI analyzes all available data related to the potential defect, issues information requests to the manufacturer, reviews any similar complaints or defects in related models, and determines the scope of the potential defect. A PE typically lasts 4-6 months and results in either closure (no defect found), upgrade to an Engineering Analysis, or a voluntary recall by the manufacturer.
Phase 3: Engineering Analysis
If the PE reveals sufficient evidence of a potential safety defect, ODI upgrades to an Engineering Analysis (EA). This is a more intensive investigation that may involve physical vehicle inspections and testing, detailed engineering review of the affected systems, analysis of crash and injury data, and expert consultations. An EA can take 1-2 years depending on the complexity of the defect.
Phase 4: Recall Request or Order
If the EA confirms a safety defect, NHTSA can request a voluntary recall or, if the manufacturer refuses, order a mandatory recall. Most manufacturers issue voluntary recalls before NHTSA reaches the order stage. The recall process then begins with owner notification and free repairs.
How Consumer Complaints Drive Investigations
Consumer complaints are a critical input to the investigation process. The more detailed and specific your complaint, the more useful it is for ODI analysts. If you experience a safety defect, file a complaint with NHTSA — your report contributes to the data that triggers investigations. Check existing complaint data on our complaint rankings page.
Frequently Asked Questions
A Preliminary Evaluation typically takes 4-6 months. If upgraded to an Engineering Analysis, the investigation can extend to 1-2 years. Some complex investigations have taken even longer, especially when they involve new technology or require extensive testing.
Yes. NHTSA publishes all open investigations on its website. You can search by vehicle year, make, and model to see if your vehicle is currently under investigation. An open investigation does not guarantee a recall will be issued.
NHTSA reviews all complaints but does not formally investigate every individual complaint. The agency looks for patterns — when multiple owners report similar problems with the same vehicle, that pattern can trigger a formal investigation. Individual complaints are important data points in this process.