Things to Look Out For When Buying a Car From a Private Seller

Get familiar with the common techniques used by unscrupulous sellers to hide problems with used vehicles.

Benjamin Hunting | 
Sep 11, 2023 | 3 min read

Young lady holding tablet with checklist standing next to a car in a parking lotShutterstock

Buying a used car or truck can be stressful enough without having to account for possible deception by the seller. It's important to always ask questions before buying. Unfortunately, there are plenty of people out there who will lie, conceal, or otherwise fudge the truth while trying to get the most money possible for their secondhand vehicle.

Here are some of the most common ways private used-car sellers might be less than honest when hawking their vehicles — and what you can do to help avoid being taken for a ride.

Double-Check for Falsified Mileage

Mileage is considered a key metric for determining a vehicle's value, as it offers insight into just how much wear it has endured. Unfortunately, some sellers — accounting for as many as 450,000 vehicles a year, according to the National Highway Traffic Safety Administration — will hack their odometer and "roll back" the numbers to make their car or truck more appealing.

Look for Error-Code Clearance

A used vehicle could have a problem that illuminates its check-engine light (CEL), but you might not be alerted to that problem during your test drive. Sellers can erase the diagnostic trouble codes that trigger a CEL by using an OBD-II scanner before you turn the key, leaving you in the dark about a problem you'll inherit if you buy that car.

Beware of Stop Leak, Stop Smoke Additives

Rather than repair a problem affecting a vehicle's drivetrain, unscrupulous sellers often try to disguise it with a Band-Aid solution. Common among these are pour-in products such as Engine Oil Stop Leak Concentrate and Radiator Stop Leak, which use chemical cocktails to soak dried-out seals in an engine or gum up holes in the cooling system that are allowing fluids to escape. These quick fixes can make it tough for you to spot leaks during a test drive or casual inspection.

Avoid Painted-Over Cosmetic Flaws

Rust and other body damage can be expensive to repair, which makes it tempting for underhanded individuals to cover up cosmetic problems with quick paint and body work. If an older vehicle has a fresh paint job, that's often a sign that there's more going on than meets the eye when it comes to the condition of its sheet metal.

Don't Cave In to Seller Pressure

Some private used-car sellers may try to convince you that you'll miss out on the deal of a lifetime if you don't make a quick decision because there's a mile-long line of other people ready to buy. The same rules that apply at a dealership apply here. Buying a car should be done on your own schedule. Don't feel pressured to make a purchase before you're ready.

Always Arrange for a Pre-Purchase Inspection

A professional mechanic is much better equipped than most buyers when it comes to used-car forensics. A pre-purchase inspection performed by a qualified technician is an affordable insurance policy that could spare you thousands of dollars in repair bills down the road. A good mechanic can catch most major problems before you plunk down your money.


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Benjamin Hunting

Benjamin Hunting is a writer and podcast host who contributes to a number of newspapers, automotive magazines, and online publications. More than a decade into his career, he enjoys keeping the shiny side up during track days and always has one too many classic vehicle projects partially disassembled in his garage at any given time. Remember, if it's not leaking, it's probably empty.