'It's Burnt:' Used Car Salesman Says Always Do This Trick When Scoping a New Car. Especially If You’re Buying

"My light stays on so I’m good."

Photo by: Unsplash.com

By: Madeleine Wagner

Oct 27, 2025 at 4:00pm ET

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It’s that small voice in the back of your head—the one that tells you to ease off and let the tailgater blow by; or keeps poking you, hinting that you’re missing something. It gets louder when the stakes are high: the right job, the right house, the right car, and rightfully so. These are big decisions that can impact your life for years.

Considering that about three out of four car sales happen on the used market, that voice does a lot of talking. Because chances are, most of us have been in the driver’s seat of a “too good to be true” deal, hoping it’s real, not just someone else’s freshly waxed headache.

What Tip Should I Know Before Buying a Used Car?

That’s where TikTok can actually come in handy. More than just dance challenges, recipes, and hot takes, some of the most useful creators on the app right now are car sales pros. Take The Vehicle Wizard (@the.vehicle.wizar), a Texas-based car dealership (DFW Auto Mill), which recently posted a tip, viewed 3,213 times, that most car buyers might miss.

“If you’re buying a car, turn on the ignition without turning on the car. See if that “check engine” light shows. Because if you turn on the ignition and the light’s off, as in there’s no check engine light, it’s burnt. Someone messed with it,” says The Vehicle Wizard.

How Does He Know For Certain?

His video was prompted by “a guy trying to sell me a car with 11 codes,” he explains.

Then he gives a small shake of his head and says, “I’ve been in this business too long.”

In the comments section, he offers more context: the check engine light wasn’t illuminating, “as if the car never came with a check engine light.”

For the record, the check engine light should flash briefly when you turn on a car. This is designed to make sure all of the dashboard lights are working properly. Redditor u/tripleriser writes, “It's actually a good thing to check when buying a car. If the light doesn't come on, someone removed the bulb and is trying to hide something.”

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Lights, Codes, Action

The comments section then lights up with more advice and a few jokes.

“Check for the airbag light too. Make sure it comes on then turns off,” says Shimi (@sh1mi11).

Then, walking into a dealership with an engine code reader is suggested: “Get a code reader. They’re inexpensive,” says drke3993 (@drke3003). “Get one like BlueDriver that can tell you how many warmups the car has had since the codes were last cleared. It could save you thousands.”

While in a quip more than a few of us might recognize, TopRamos (@topramos11) says, “My light stays on, so I'm good.”

Gallery: Most-Reliable Used Car Brands

Source: Motor1

Other Things to Look Out For

In a subsequent TikTok, The Vehicle Wizard agreed with getting a scanner. Then he offered an explanation: “Put in the OBD. If there are any incompletes that have not been completed, then the car needs to be driven.” (OBD stands for on-board diagnostics.)

He says this is “just in case, you drive it a little bit home and there was two or three incompletes, the check engine light might pop up. So drive the car, if there are eight incompletes you’ll have to drive it like 50 miles to make sure you’re not going to get a ‘check engine light.’”

“OBD, incompletes, make sure they’re all completed,” he says.

The driving allows the computers to “reset,” so you can get an accurate picture of what’s happening with the vehicle. Of course, when purchasing a used car, it’s always a good idea to get it inspected by a trusted mechanic. Hopefully, that’ll help avoid any unhappy surprises.

In an email to Motor1, AJ, a representative for the dealership, writes, “It’s nice to see that video going around. It is definitely something to look out for when purchasing a used car.”