Bought a used car as is and it broke down?

Dealers must post a Buyers Guide on every used car they offer for sale, and give you the final version when you buy. It says whether the car comes with a warranty or is sold “as is.” If the “As Is - No Dealer Warranty” box is checked, the FTC says the dealer won't pay for any problems or repairs. You take on the risk of anything that goes wrong after the sale.

• The final Buyers Guide is part of your sales contract and overrides anything different in it. If the Guide promised a warranty and the contract says "as is," you get the warranty.
• The dealer can't say anything, out loud or in writing, that contradicts the Buyers Guide. Still, the FTC warns that spoken promises are hard to enforce, so check whether a promised repair was written down.
• If the "Implied Warranties Only" box is checked instead, the dealer made no extra promises. But your state's implied warranties may give you the right to have the dealer fix serious problems you couldn't see when you bought the car (see below).

Bought from a private seller? The Buyers Guide rule covers dealers: anyone who sold or offered five or more used cars in the past 12 months. New York's DMV warns that private buyers are unlikely to get any warranty and are on their own to resolve problems. A seller who lied about the car is a different matter (see below).

Implied warranties are unwritten promises that come with a sale under state law. The FTC describes two:

• Merchantability: the car will do what a car is supposed to do. It covers basic functions, not everything that can go wrong.
• Fitness for a particular purpose: if the dealer told you a car was right for a job, like towing your trailer, it promised the car can do that job.

A used car without a written warranty still has implied warranties unless it was sold “as is.” The FTC says they can last as long as four years, depending on the state. To use one, you need to show the problem was there when you bought the car, and the dealer may disagree.

Some states limit or ban “as is” sales. There, the federal rule doesn't give dealers the right to sell “as is,” and they must use the “Implied Warranties Only” Buyers Guide instead. Other states allow “as is” sales only if the dealer uses special wording or a separate document. And a dealer that gives you any written warranty can't take away your implied warranties.

The FTC suggests asking your state attorney general what your state requires for “as is” sales.

If you bought a service contract (often called an extended warranty) from the dealer at the sale or within 90 days after it, the FTC says the dealer can't take away implied warranties on the parts that contract covers. That comes from the federal Magnuson-Moss Warranty Act. The FTC's example: a car sold “as is” normally has no implied warranties, but if you bought a service contract covering the engine, you automatically get implied warranties on the engine.

Those warranties may protect you beyond what the service contract covers. The Buyers Guide's service contract box says the same thing: buying one within 90 days may give you extra rights under your state's implied warranties.

File a claim under the service contract too, the way the contract says. The FTC suggests getting written confirmation that your service contract is in effect.

Lemon laws are state laws, and they differ a lot. Florida's, for example, covers only new and demonstrator vehicles. Some states also protect used-car buyers. Two examples:

• New York: a New York dealer must give you a written warranty on a used car you bought mainly for personal use that cost at least $1,500, had fewer than 100,000 miles, and was past 18,000 miles or two years old. It lasts 30 to 90 days depending on the miles (90 days or 4,000 miles for a car with 18,001 to 36,000 miles) and covers the engine, transmission, brakes, steering, and other major parts. If the problem isn't fixed after three tries, or the car is out of service 15 days or more, you can ask for arbitration and may get a full refund.
• Massachusetts: a Massachusetts dealer must give you a written warranty on a used car you bought for personal or family use that cost at least $700 and had fewer than 125,000 miles, and it can't be waived. It lasts 30 to 90 days depending on the miles (90 days or 3,750 miles for a car with fewer than 40,000 miles). If the same defect isn't fixed after three tries, you can return the car for the repurchase price. Arbitration requests are due within six months of the sale.

Report a problem to the dealer as soon as it shows up. In New York, if you report it during the warranty, the dealer must fix it even if the warranty runs out first. Rules vary by state, so ask your state consumer protection office whether your state has a used-car lemon law and what its deadlines are.

“As is” means the dealer didn't promise the car would keep working. It doesn't let a dealer lie about the car. Under the FTC's Used Car Rule, it's deceptive for a dealer to:

• Misrepresent a used car's mechanical condition.
• Misrepresent the terms of a warranty.
• Say a car comes with a warranty when it doesn't.

So if a dealer told you the transmission was just rebuilt, and it wasn't, that's a different problem from an honest breakdown. Save the ad, texts, emails, and notes on what you were told, and get a mechanic's findings in writing. Then report it to your state attorney general and to the FTC at ReportFraud.ftc.gov. A local consumer attorney can tell you whether you have a claim.

Found a salvage or flood history nobody mentioned? See what to do about a hidden title brand.

Someone other than the dealer may have to pay for the fix.

• Recalls. Search the VIN in NHTSA's recall lookup for unrepaired safety recalls. NHTSA says to contact your local dealership to fix a recalled part for free. Its lookup doesn't show recalls more than 15 years old, and very new recalls can take time to appear.
• The manufacturer's warranty. On a newer car, the factory warranty may still cover some parts, and the dealer may have checked “Manufacturer's warranty still applies” on the Buyers Guide. The FTC suggests calling a dealership with the VIN to confirm what's covered and until when.
• A service contract. If you bought one, file a claim the way it says (see above).

1. If the car isn't safe to drive, park it and have it towed.
2. Find your Buyers Guide and contract. Note which box was checked (As Is, Implied Warranties Only, or Warranty), and whether and when you bought a service contract.
3. Check for recalls and any manufacturer's warranty before you pay for a repair.
4. Get a written diagnosis from a mechanic you choose: what failed, and whether it looks like it was there when you bought the car.
5. Write to the dealer. Describe the problem, when it started, and the mileage. Say which right you're relying on (a warranty, an implied warranty, a service contract, your state's lemon law, or something the dealer told you that wasn't true), what you want, and by when. Keep a copy.
6. If the dealer won't help, contact your state attorney general's consumer protection office. The FTC also points to dispute resolution programs and small claims court.

Under the federal Magnuson-Moss Warranty Act, you can sue over a broken written or implied warranty or a service contract, and if you win, the FTC says you can recover reasonable attorney fees and court costs. A lawyer can tell you if it applies to you.