How DefectFile counts, matches, and ranks

Every figure on this site is a public record organized by DefectFile. This page states exactly how, so that any number can be checked against its source.

Snapshot and updates	This build was generated on October 14, 2026. The site re-downloads every source and rebuilds itself on the 3rd of each month. NHTSA publishes its files daily and Transport Canada monthly, so a record can be up to a month behind the agencies.
Sources	US complaints, recalls, defect investigations, and manufacturer communications from the National Highway Traffic Safety Administration's public flat files; vehicle recalls from Transport Canada's Vehicle Recalls Database (Open Government Licence - Canada); vehicle specifications and fuel economy from the US EPA. All are public records; DefectFile adds organization, matching, and commentary, and no data of its own.
Complaint unit	The federal complaint file has one row per complaint per component named. DefectFile keeps both units and labels them: complaint records (rows) power the fault profile and family bars, where a complaint naming two systems rightly counts once in each; distinct complaints (unique ODI numbers) are used for every headline count, ranking, and comparison. The site currently holds 1.58 million distinct complaints across 2.15 million records.
Deduplication	Complaints are deduplicated by ODI number for distinct counts. Recalls are grouped by campaign number. Investigations by action number. Service bulletins are stored once per bulletin per vehicle and shown once per document ID per month. Canadian recalls once per recall number per vehicle. Amended federal records replace earlier versions in NHTSA's own file; DefectFile does not track amendment history.
Component families	NHTSA has used 763 different component labels over the file's history, across two taxonomies. DefectFile groups them into 25 families by longest-prefix rules (for example every SERVICE BRAKES variant becomes brakes; the older ENGINE AND ENGINE COOLING label merges into engine because the modern taxonomy does not separate them). Roughly 117,000 records filed under unknown or unclassifiable components are excluded from rankings. The complete 45-rule mapping from raw labels to families is published as component-families.csv, and the 304-part template as parts-template.csv.
Known issues	The Known issues cards are the component families with the most records against a vehicle. Their counts and crash, fire, injury, and death figures belong to the whole family. For 25 vehicles an editor has written a note describing one frequently reported issue in that family; the note is labelled as such and carries no numbers, because DefectFile has not measured what share of the family's records concern it. The owner excerpt shown is a single complaint from that family chosen by length, and may not describe the named issue. All editorial notes are written by a person, not generated from the data.
Crash and fire figures	Attached at the component-family level only, from the complaint file's own crash, fire, injury, and death fields as filed by the owner. They are never attributed to a specific named issue.
Vehicle matching	Make and model names are normalized to upper case with whitespace collapsed; a small alias table merges spelling variants (Mercedes Benz and Mercedes-Benz, for example). A vehicle is a make, model, and model year as the federal file records them. Vehicle pages exist for every combination with at least 100 complaint records; model pages for every model with two or more years on record.
Configuration shown	EPA names every configuration with drivetrain and variant suffixes, so specifications are matched by normalized name prefix and one example configuration is shown, labelled as such. The complaints, recalls, investigations, and bulletins on a page cover every configuration of that model year. Heavy-duty trucks above 8,500 lb GVWR are not EPA-rated and are labelled so.
Recalls	US recall campaigns are matched to the make, model, and model year the campaign lists. A campaign on a page means the model year was covered, not that a particular car was affected or that its repair is outstanding; only a VIN lookup with the manufacturer or NHTSA answers that. Safety-recall remedies are normally provided at no charge. Under US federal law the mandatory free remedy applies when the vehicle was no more than 15 years old at the time the defect was determined; manufacturers often cover older vehicles voluntarily. Canadian rules differ. Confirm eligibility with the manufacturer using the VIN.
Canadian recalls	Transport Canada records are matched by normalized model name (prefix, containment, or shared leading token), because the two agencies spell models differently. A Canadian-market variant can therefore appear under the closest US model name. Only Car, SUV, Light Truck & Van, and Minivan categories are loaded. Every Canadian recall links to its record at Transport Canada.
Investigations and bulletins	Investigations are shown per vehicle with status and, where one resulted, the recall campaign. Manufacturer communications are shown per vehicle with the type NHTSA records (service bulletin, service campaign, warranty extension, software update); warranty extensions are surfaced first because they may pay for a repair that no recall covers. Bulletin summaries are NHTSA's, truncated at a sentence boundary; each vehicle page shows up to 30 with a count of the rest.
Rankings and comparisons	Leaderboards rank distinct complaints to date and say so. Model pages additionally rank each model year on distinct complaints filed within eight years of the model year, so that a 1997 and a 2015 are compared on the same exposure window; the two newest years and years before 1990 (the file begins in 1995) are excluded from that ranking. No ranking is adjusted for sales volume, registrations, or vehicles still on the road, because those figures are not public in usable form. A high total can reflect a best-selling year as much as a bad one.
Failure timing	The When it fails histograms use two owner-supplied fields from each complaint: the reported failure date (shown as vehicle age, the failure year minus the model year) and the reported odometer reading (shown in 20,000-mile bands, kept only between 500 and 500,000 miles). Many complaints omit or garble these fields, so each chart states how many complaints it is based on; neither figure is verified, and charts are drawn only when at least 30 complaints have a usable value. Reporting behavior shapes these curves along with the vehicle itself.
Parts	Under a known issue, a part appears only when the editorial note for that vehicle names it, and it is labelled as named by the editor rather than by any federal record. Every vehicle also has a separate parts search directory: the generic parts a vehicle of that fuel type and era has, filtered by fuel type and model year but not by engine, trim, or brake type. Neither is a diagnosis or a fitment guarantee; confirm fitment before buying.
Affiliate links	Part links open eBay searches through the eBay Partner Network, and DefectFile may earn a commission on qualifying purchases. Links carry no prices and do not influence any count, ranking, family assignment, or editorial note; the same page would rank the same way with the links removed. No manufacturer, dealer, or parts seller pays for placement or has reviewed any content.
Corrections	Every page carries a link to report an error to corrections@defectfile.com. Corrections that change a published figure are noted on the affected article with the date. Vehicle pages regenerate monthly, so a correction to the pipeline reaches every page at the next build.

Component families

The 24 families used throughout the site and their identifiers in the published mapping file.

Family	Identifier
Driver assistance	adas
Air bags	airbags
Brakes	brakes
Electrical system	electrical
Engine & cooling	engine
Equipment & interior	equipment
Stability control	esc
Fuel system	fuel
Diesel fuel system	fuel-diesel
Hybrid & EV system	hybrid-ev
Latches & locks	latches
Lighting	lighting
Parking brake	parking-brake
Power train	powertrain
Seat belts	seat-belts
Seats	seats
Speed control	speed-control
Steering	steering
Body & structure	structure
Suspension	suspension
Tires	tires
Trailer equipment	trailer
Glass & wipers	visibility
Wheels	wheels