When you buy a toaster that turns out to be defective, it’s not a big deal. You either return it or toss it and buy a new one. But when a car has defects, the actions you must take are complicated and costly. That’s why most buyers do everything in their power to avoid purchasing a car with preexisting issues. These defective vehicles are often known as “lemons.”

Even brand-new cars can have defects that earn them the title of a lemon. But used cars are more problematic. They could have defects the previous owners don’t want to deal with and aren’t forthright about, or they could have problems that stem from faulty maintenance and repair.

How to identify a lemon

How can you minimize your chances of parking a lemon in your garage? Here are four tips to help you during the car-shopping process.

1. Pay attention to the Buyer’s Guide

Buying from a dealer? They’re required by law to post a Buyer’s Guide in the car, usually in the window. Here’s what needs to be in that guide, according to the Federal Trade Commission:

• Whether the vehicle is sold “as is” or has a warranty
• Information about the car’s major electrical and mechanical systems
• What percentage of any repair costs the dealer will cover if the car is under warranty

This information can help you understand what could go wrong with the car and the dealer’s responsibility. Be sure to keep this in a safe place if you purchase the vehicle, so you can refer to it as needed.

2. Get the vehicle’s history

These days, reports from companies like Carfax and AutoCheck can give you the history of a car, including accidents, damage, odometer readings and recalls. Many dealers will make this report available to the buyer. But if there’s not one to review, you can order your own with the Vehicle Identification Number.

3. Give the car a good inspection

You don’t have to be a trained mechanic to check for signs that a used car has been in an accident or has had many repairs. Simply being observant and thorough can help you identify whether the vehicle has had bodywork or replaced parts. Here’s what to look for:

• Check for chips, dents, or misaligned panels that indicate body repair. You should also look for signs that the car was repainted.
• Open and close the doors, trunk, and hood to ensure the seal is tight and there are no mildew or mold odors.
• Lift the hood. If any areas are blackened, it may show that the car has overheated or had an engine fire. There should not be any corrosion or worn belts or hoses. Wet areas may be a sign that fluids are leaking.
• Check fluids. If you’re comfortable doing so, check the oil when the car is cool. It should be at the right level and a dark brown or black color — never orange or light brown — and it should not have any particles in it. You can also check the transmission fluid after the car has been driven to ensure it’s dark to light red and not brown, black, or golden.
• Look at the tires. Wear should be even, and there shouldn’t be extensive wear on the outside shoulder.

4. Enlist the help of a mechanic

For between $100 and $150, diagnostic auto mechanics can assess a car’s condition, and that’s money well spent if you want to avoid major problems and repairs. Dealers will usually be fine with you taking the car for an inspection. But you may need to ask private sellers to meet you at the mechanic with the vehicle.

The mechanic will look for signs of repairs that indicate damage or an ongoing mechanical problem. If you uncover damage that wasn’t listed by the seller or in the car report, you can rely on the mechanic’s expertise to decide if the car is still a worthwhile purchase — probably at a negotiated, lower price — or if you should walk away.