A Philadelphia mechanic is going viral after warning car buyers about a hidden red flag to watch for when purchasing a used vehicle.
In a TikTok posted by Harris Automotive (@harrisautomotive), the mechanic shares a story about a woman who brought in her recently purchased car for an inspection—and immediately failed.
“When you buy a car used, always check for this,” he writes in the caption. “This is a must-see entire video.”
The clip, which has garnered more than 16,800 views as of this writing, quickly caught the attention of drivers who shared their own stories about sketchy used car deals and missed warning signs.
What Was Wrong With the Car?
According to the mechanic, the woman had purchased her car from a used car lot and brought it in for a standard inspection. But when he turned on the ignition, something didn’t add up. The check engine light never came on.
“Anytime you have a vehicle, and that vehicle starts, your check engine lightbulb should illuminate,” he explains.
Because it didn’t, the car immediately failed inspection. The mechanic soon discovered that the vehicle had fake inspection stickers on the windshield—ones suggesting it had last been inspected in September. “Dummy stickers, as we call them,” he says, referring to counterfeit inspection labels used to disguise vehicles that haven’t passed safety or emissions checks.
In the video, he points to where the light should appear on the dashboard before disassembling the car to reveal the real issue.
“This one right here in the middle looks like someone damaged it and popped the bulb out,” he tells viewers, holding up the missing piece.
He says the car would be repaired, but he ended with a warning for anyone shopping secondhand: “Watch where you buy cars from.”
In the caption, he adds, “One of the first things you look out for when you’re buying a used car.”
Why Would The Check Engine Bulb Be Out—And How Can I Check Mine?
If the check engine light on a car doesn’t come on at startup, that’s typically a sign that either the bulb is burned out or someone intentionally removed it.
The light is designed to alert drivers to problems with the engine or transmission, so without it, you’re driving blind to potential issues and will likely fail an emissions inspection, as the mechanic from Harris Automotive shows.
Tampering with a check engine light is illegal, but it happens more often than people realize. Sellers sometimes cover the light with tape, pull the bulb, or rewire it to hide existing problems. When you turn on the ignition, the check engine light should briefly illuminate during the system’s self-test. If it doesn’t, assume something’s wrong.
There are several ways to check for tampering before buying used. Start by turning the key to the “on” position without cranking the engine; all the dashboard lights should flash, including the check engine light. If it stays dark, that’s a red flag.
As some commenters suggested, a quick scan of the vehicle with an OBD II reader can also reveal whether the system is hiding any trouble codes. If you suspect the instrument cluster’s been tampered with, have an independent mechanic inspect the wiring and circuit board before you drive anything home.
More Tips For Buying Used
People who saw the mechanic’s video chimed in with their own experiences—and plenty of advice for anyone shopping for a used car. One viewer urged others to come prepared, writing, “That’s why you need a scanner. Never buy a car without scanning it first.”
Others related to the woman’s story all too well.
“Yupp happened to me,” one woman shared. “I bought my first car from someone on Facebook, and they took the check engine light out, and when I had it scanned, it literally had over 30 codes. I scrapped that car immediately.”
Another echoed that sentiment, recalling, “That happened to me. Didn’t realize it until the car cut off while I was driving.”
Some commenters praised the mechanic for catching the problem and warning others about the scam.
“Test drive it,” one suggested. “Right to some auto store to have it checked for codes. If the dealership is on the up and up, they don’t care.”
Another user applauded the video, saying, “What an awesome video. What a sneaky world.”
Others were appreciative of the advice.
“Omg!! You are the best!!” one wrote.
“Great knowledge,” added another. “Much appreciated.”
A third summed up the general feeling with, “Oh wow, thanks for that.”
Motor1 has reached out to Harris Automotive via a direct message on TikTok. We’ll be sure to update this if they respond.