Auto repair warranty
Most repair shops give a written parts and labor warranty, commonly 12 months or 12,000 miles, with many offering 24 months/24,000 miles or more. Write the terms on the estimate and invoice: what is covered, for how long, and what isn’t. And customers can use an independent shop without voiding their car’s factory warranty: under the Magnuson-Moss Warranty Act, a manufacturer can’t deny coverage just because someone else did the work or used aftermarket parts.
Common warranty terms
| Term | Typical for |
|---|---|
| 90 days / 4,000 miles | Used parts, some budget shops |
| 12 months / 12,000 miles | Many independent shops |
| 24 months / 24,000 miles | Network shops and many independents |
| 36 months / 36,000 miles | Premium programs and some parts lines |
Your warranty can’t be better than you can afford to honor. Check what your parts suppliers cover, including labor reimbursement.
What to write down
- Duration in months and miles, whichever comes first
- What’s covered: parts, labor or both
- Exclusions: customer-supplied parts, used parts, abuse, racing, commercial use, wear items
- How to claim: bring it back to you; what happens if the customer is far away
- That the warranty doesn’t limit rights the customer has under state law
Factory warranty and Magnuson-Moss
The FTC says it is illegal for a manufacturer or dealer to void a warranty or deny coverage simply because the customer had routine maintenance or repairs done elsewhere, or used aftermarket or recycled parts. The manufacturer can deny a specific claim only if it shows that the aftermarket part or the independent work caused the damage. Keep your records so customers can prove maintenance was done on time.
Handling a comeback
- Look up the original repair order: date, mileage, parts and the technician.
- Diagnose before deciding: is it the same failure or a new one?
- If covered, do the work at no charge and write a $0 repair order that references the original.
- File the parts warranty claim with your supplier, and return the part as a warranty core.
Warranty on every invoice. WrenchTicket has a warranty field that prints your terms on the estimate and invoice, and marks replaced parts that go back to the supplier for warranty. Pro keeps every repair order searchable for comebacks. $15 a month.
Write an invoiceQuestions
Do I have to offer a warranty?
No law requires a specific written warranty for most repairs, but state law may imply that work is done in a workmanlike manner. A clear written warranty sets expectations and builds trust.
Does an oil change at a quick lube void my factory warranty?
No. Keep the receipt showing the date, mileage and the oil used.
Can I exclude customer-supplied parts?
Yes. Say so on the estimate before the work.
Checked against the Magnuson-Moss Warranty Act and FTC consumer guidance “Auto Warranties and Auto Service Contracts”, November 2026. Warranty terms are market examples.
Free PDF
Auto repair paperwork cheat sheet
What every estimate, repair order and invoice must show, the rules of the 10 largest states and a printable added-work approval log. We email it to you.