Service bulletins and campaigns, by the number on the letter

A technical service bulletin is the manufacturer telling its dealers how to diagnose or repair a known condition. It is not a recall, not a finding that the vehicle is defective, and the work is not automatically free. A service campaign, a warranty extension or an over-the-air update is the same kind of filing with a different promise attached: usually work the manufacturer pays for on the vehicles it names, within the terms the document sets, and usually announced by letter — which is why its number is the one people search.

A safety recall is different in law: it carries an NHTSA campaign number, the manufacturer must repair it free for vehicles up to fifteen years old, and it has its own pages here, by NHTSA’s number and by the manufacturer’s.

What is here: 6,971 of the roughly 120,000 distinct bulletin numbers NHTSA holds for 2016-and-later model years — the kinds an owner is written to about, and the bulletins this site’s vehicle pages already show. The rest are dealer repair instructions nobody outside a service department types into a search box; the vehicle page’s count includes them.