How to Write a Parts and Labor Warranty as a Mechanic (and What Federal Law Requires)

Updated 2026-10-17. Sources are listed at the end.

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This is general information, not legal or tax advice. Rules vary by state and change often. Confirm with the official source linked in each section, or with a licensed attorney, CPA or insurance agent, before you act.

“What’s your warranty?” is one of the first questions a new customer asks. A clear written answer wins jobs and settles comebacks. A vague one starts arguments. And once you put a warranty in writing, federal law has something to say about how you word it.

When federal warranty law applies to a repair

The federal law on consumer product warranties is the Magnuson-Moss Warranty Act. The FTC’s Businessperson’s Guide to Federal Warranty Law explains its scope (FTC):

The Act does not require you to offer a written warranty.
It covers only written warranties, not oral ones.
It does not apply to warranties on services alone. But the FTC says: “if your warranty covers both the parts provided for a repair and the workmanship in making that repair, the Act does apply to you.”
It covers consumer products, the kind normally used for personal, family or household purposes. A family car qualifies. Fleet or commercial work may be different.

Most mechanic warranties cover “parts and labor,” so assume the Act applies when you write one.

What the Act requires once you give a written warranty

Title it “full” or “limited” (written warranties on consumer products costing more than $10).
State the terms clearly in one easy-to-read document (the FTC’s Disclosure Rule, for products over $15).
Make it available before the sale (Pre-Sale Availability Rule, over $15). If you sell somewhere other than your place of business, as a mobile mechanic does, the FTC says to offer the customer copies of the written warranty before the sale is completed.

“Full” or “limited”? Under the FTC’s guide, a warranty is “full” only if all five of these are true: you don’t limit implied warranties; you cover anyone who owns the product during the warranty; service is free; the customer can choose a replacement or a refund if you can’t fix it after a reasonable number of tries; and you impose no unreasonable duties. Almost every repair warranty (for example, “labor covered 12 months, parts per the manufacturer”) is a limited warranty. Title it that way.

What you can’t do

Disclaim implied warranties. If you give a written warranty, the Act prohibits disclaiming implied warranties (like merchantability). With a limited warranty you may limit their duration to the length of your warranty.
Write deceptive terms, for example coverage that sounds broad but covers nothing.
Use tie-ins. You generally can’t condition the warranty on the customer buying some other product or service from a particular company, unless you provide it free or the FTC grants a waiver. You can exclude damage caused by parts or service you didn’t provide.

A sample policy (adapt it, and have it reviewed)

Limited Warranty, [Business Name] What’s covered: Defects in parts we supplied and in our workmanship on the repair listed on this invoice. How long: [12 months or 12,000 miles], whichever comes first, from the invoice date. What we’ll do: Repair the covered defect at no charge for parts or labor, at your location or a location we arrange. Not covered: Customer-supplied parts (labor only, if stated); damage from accidents, abuse, overheating, lack of maintenance, or repairs by others; normal wear items unless stated; incidental or consequential damages, where state law allows that exclusion. How to get service: Contact us at [phone/email] with your invoice number before having the problem repaired elsewhere. Parts manufacturer warranties: Passed through to you. Ask for details. Your rights: This warranty gives you specific legal rights, and you may also have other rights which vary from state to state. Any implied warranties are limited to the duration of this warranty, where state law allows.

Mobile-specific choices to make up front:

Customer-supplied parts: most mobile techs warrant labor only, or nothing. Say so in writing before you install them.
“Lifetime” parts: the FTC’s advertising guides warn that “lifetime” is confusing. Say whose life: the car’s, the original owner’s or the part’s.
Fleet accounts: put warranty terms in the account agreement. See fleet maintenance accounts.

Some states also require warranty terms on the invoice. Florida’s invoice rules include what is guaranteed and the time and mileage period (FDACS). See estimate & invoice requirements.

Price comebacks into your rate

A warranty is a cost. Every comeback is unpaid time plus a trip. Estimate your own comeback hours from your records (for example, if 2% of billed hours come back) and reduce your billable hours to match in the labor rate & break-even calculator. Your rate will cover the warranty instead of your profit absorbing it. Good parts, OEM procedures and a final road test are the cheapest warranty insurance there is. For liability beyond comebacks, see mobile mechanic insurance types.

Sources

FTC, Businessperson’s Guide to Federal Warranty Law: https://www.ftc.gov/business-guidance/resources/businesspersons-guide-federal-warranty-law
Florida FDACS, Motor Vehicle Repair FAQ: https://www.fdacs.gov/Business-Services/Motor-Vehicle-Repair