New Car Warranty Explained: What Is Covered and What Voids It

A new car warranty is the manufacturer's promise to fix defects in the car for a set time or mileage at no charge. It is included in the price; you do not buy it separately. It is also several warranties, not one, and each has its own clock. The FTC describes a warranty as "a promise to fix certain defects or malfunctions during a specific timeframe after you buy a vehicle."

The exact terms for any car are in its warranty booklet, which is in the glovebox and usually on the manufacturer's website. Read the booklet for the model year you are buying. What follows explains what you will find there.

The coverages, side by side

Limits are written as years or miles, "whichever comes first". The clock starts on the in-service date, the day the car was first sold or put into use as a demo or loaner, not the day you bought it.

Coverage	What it generally covers	What to look up in the booklet
Basic or "bumper-to-bumper"	Defects in most parts of the car	Years and miles; the list of exclusions
Powertrain	Engine, transmission and drive components	Usually runs longer than basic coverage; which parts count
Corrosion or perforation	Rust that eats through a body panel from the inside	Whether surface rust is covered (often not, or only briefly)
Emissions	Parts that control emissions, under federal rules	See below; some states add longer coverage
Hybrid or EV components	High-voltage battery and electric drive parts	Years, miles, and any capacity threshold
Roadside assistance	Towing, jump starts, lockouts	A service, not a repair warranty; term varies
Adjustments and wear items	Alignments, brake pads, wipers, bulbs	Often covered only for a short initial period, if at all

Terms differ a lot between brands. A long powertrain warranty is a real point of difference when comparing two cars, so write the numbers down for each finalist.

Bumper-to-bumper does not mean everything

The name is marketing. Basic warranties exclude normal wear (tires, brake pads, clutches, wiper blades), routine maintenance, damage from accidents, misuse, weather or lack of maintenance, and cosmetic changes over time. Tires are usually covered by the tire maker's own warranty.

Emissions warranty

This one is set by federal rules, not by the manufacturer's generosity. According to the EPA, emission-related parts are covered for the first 2 years or 24,000 miles, whichever comes first, and a short list of major emission control components is covered for 8 years or 80,000 miles. The EPA's consumer page lists those major components as the catalytic converters, the electronic emissions control unit, and the onboard diagnostic device. Your booklet has the full parts list for your car. Some states have their own, longer emissions warranty requirements; the booklet will have a section for those states.

EV and hybrid battery coverage

The battery is the most expensive part of an electric car, and it has its own warranty. The Department of Energy notes that many manufacturers offer 8-year/100,000-mile warranties on EV batteries. Check three things in the booklet:

The years and miles.
Whether it covers loss of capacity or only outright failure, and if capacity, the percentage that triggers a repair.
Whether the remedy is a new battery, a refurbished one, or repair of individual modules.

Federal rules on battery warranties for newer model years have been changing, so rely on the written warranty for the specific car and not on a general rule. Used EV battery health covers how this plays out on a used car.

What does not void your warranty

This is the part people most often get wrong, usually because someone told them they must service the car at the dealer. The federal Magnuson-Moss Warranty Act governs warranties on consumer products, and the FTC's guidance for car owners is direct.

You can have maintenance done anywhere, or do it yourself. The FTC says "it's illegal for a dealer to deny your warranty coverage" simply because someone other than the dealer did routine maintenance or repairs.
You can use aftermarket or recycled parts. Using them does not by itself end warranty coverage.
A manufacturer generally cannot require its own branded parts or service as a condition of the warranty. The FTC's business guidance calls these "tie-in" provisions and says they are generally prohibited. The main exception is when the part or service is provided free under the warranty, in which case the manufacturer can choose where the free work is done and which parts are used.

What can get a claim denied

A warranty is rarely "voided" as a whole. What happens is that a specific repair is denied because of a specific cause.

A part or repair caused the damage. If an aftermarket or recycled part was defective or installed wrong and it damaged a covered part, the claim for that damage can be denied. The FTC says the manufacturer or dealer "must prove the aftermarket or recycled part caused the damage" first.
Missed maintenance. If you skipped the scheduled services in the owner's manual and the failure is related, expect a denial. The FTC notes the warranty company can ask for your maintenance records.
Misuse or modification. Racing, overloading, towing beyond the rated limit, or changes such as engine tuning can lead to denials for related failures. The booklet lists these.
Damage and environment. Collisions, floods, hail and the like are insurance matters, not warranty ones.
Title brands. Many booklets cancel coverage if the car is declared a total loss or given a salvage title. See title brands: salvage and rebuilt.

Protect yourself with records

Follow the maintenance schedule in the owner's manual, including the "severe use" schedule if it applies to your driving.
Keep dated receipts showing the mileage, the work done, and the parts and fluids used. If you do your own oil changes, keep the receipts for oil and filters and a simple log.
Report problems promptly and in writing while the car is still under warranty. A repair order that shows you raised the issue before coverage expired is valuable if the fix takes more than one visit.

How to make a claim

Take the car to a franchised dealer for the brand. It does not have to be the one you bought from.
Describe the symptom, not your diagnosis, and ask for it to be written on the repair order.
Get a copy of the repair order every time, even if the answer is "could not duplicate".
If a claim is denied, ask for the reason in writing, including what evidence shows the cause.
Escalate to the manufacturer's customer assistance line, listed in the warranty booklet.
If that fails, the booklet describes the dispute process. Your state attorney general's office can explain your options, and every state has some form of lemon law for new cars with repeated serious defects. The rules and deadlines vary by state, so check your attorney general's website.

Safety recalls are separate from the warranty and are fixed free regardless of warranty status. Checking recalls before you buy shows how to look them up.

Transferability

Most factory warranties follow the car, so a second owner gets whatever time and miles remain. There are exceptions worth checking in the booklet: some brands give a longer powertrain term to the original owner only, and some require a transfer form or fee. If you are buying a nearly new used car, ask a dealer for the brand to look up the in-service date and remaining coverage by VIN. A manufacturer certified pre-owned program usually adds coverage on top.

When the warranty runs out

You will probably be offered an extended warranty when you buy. That product is a service contract, sold separately, and the FTC is clear that it is not a warranty under federal law. You do not have to decide on the day you buy the car. Extended warranties and service contracts explains how to evaluate one.

The short version