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'Don’t See This Every Day:' Toyota RAV4 Goes In for Engine Issue. Then the Mechanic Finds Something Unusual In the Air Filter

"It’s now making essential oils when they do an oil change."

Rav4 Engine Issue Update

Photo by: Unsplash.com

Steve Ecker

By: Steve Ecker

Sep 30, 2025 at 10:00am ET

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A mechanic discovers something unusual in an air filter when working on a 2020 Toyota Rav4.

In a TikTok that’s generated over 256,300 views as of this writing, Kris (@fixwithkris) reveals what he located inside the air filter that caused the check engine light to turn on.

“You guys have to check this out,” Kris begins.

He says a customer brought in a 2020 Toyota Rav4 for service to diagnose what caused the check engine light to appear. The codes determined that the issue was with the mass air flow sensor.

The mechanic begins to dig around the engine to see what exactly is going on. He starts by looking inside the air filter box and finds a white aftermarket filter. Next, he checks the mass air flow sensor and has no issues with that either.

After checking these two components, the mechanic decides to look inside where the mass air flow sensor usually sits.

What’s Wrong With the Mass Air Flow Sensor?

“You look inside, we got a smiley face. The customer has installed an air freshener in their air box because they want their air to smell good inside the car,” Kris shares.

Kris pulls out the hanging air freshener from the air filter box.

“You don’t see this every day,” Kris says.

Kris removes the air freshener and comments, “Smells fruity.”

“I’m sure the engine enjoyed it,” Kris concludes.

Gallery: 2020 Toyota RAV4 TRD Off-Road: Drive Notes

2020 Toyota RAV4 TRD Off-Road: Drive Notes

Commenters Chimed In

This move baffled the mechanic and viewers.

“So he put that in, got a check engine light and couldn't connect the dots,” one TikTok commenter questioned.

“That should be in the cabin air filter,” another suggested.

“Well at least the problem was just there smiling at you,” a third replied.

While other viewers took the opportunity to poke fun at the engine inhaling the fruity scents of the air freshener.

“The engine ‘I can’t breathe but I smell good’,” one commenter shared.

“Engine: hmm smells good in here,” another added.

“It’s now making essential oils when they do an oil change,” a third joked.

What Causes the Mass Airflow Sensor to Turn On the Check Engine Light?

The mass airflow (MAF) sensor will cause the check engine light to turn on if the sensor malfunctions, Primary Care Auto Repair reports.

The sensor will go off as it indirectly creates problems in the engine's combustion chamber when the sensor is faulty. The error code will get to the main computer's chip, triggering the check engine light.

Additional symptoms of a malfunctioning MAF sensor are rough engine lag, performance issues, black exhaust smoke, acceleration lag, and reduced fuel economy.

When the sensor is working properly, the MAF sensor converts airflow measurements into frequency signals or voltage, CarParts reports.

What Are Ways To Make Your Car Smell Better?

Putting an air freshener inside your air filter box may not be the best idea. The experts from Big’s Mobile Detailing suggested the following to keep your car smelling fresh:

No Eating In The Car: This is the most common habit that can lead to dirt and smelly cars.
Clean Your Air Vents: Dust and debris shelter within the vents. When the air blows, the unpleasant odors of the dust and debris will spread throughout the car. A small brush can easily clean up the vents.
Use an Air Freshener: These come in plugins, vent clips, or sprays. Be mindful of which product is selected, as some contain harmful chemicals.
Use Baking Soda: Natural odor absorber that can be sprinkled on seats and carpet to eliminate odor. Additionally, an opened box can be left in the car overnight.
Dryer Sheets and Fabric Fresheners: Dryer sheets can be tucked under your seats, or a spray can be applied to seats and carpet.
Clean Air Conditioning System: To clean this, turn off the engine and spray a disinfectant into the air intake vents with the air conditioning on.
Keep Windows Open: By circulating fresh air into the car, any lingering musty air gets cleared out.
Use Essential Oils: Put a few drops of essential oil onto a cotton ball and place the ball in a cup holder.
Use Coffee Grounds: Place a small bowl of grounds underneath your seat and let it sit overnight.
Clean Up Spills Immediately: Use carpet cleaner to remove spills and a damp cloth to remove any residue.
Clean the Matts: Remove and shake out matts to remove dirt and dust.
No Smoking in the Car: Smoke is absorbed by the car interior quickly.
Trunk Maintenance: Remove any wet or damp items promptly and regularly clear out gym clothes, supplies, or any other items.

What do you think?

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By using these expert cleaning habits and hacks, your car will be smelling fresh and clean.

Motor1 has contacted Kris via TikTok direct message. The story will be updated if he replies.

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