Musty smell will not go away in my used Prius

Discussion in 'Gen 3 Prius Main Forum' started by sanshan, Aug 25, 2025 at 2:37 PM.

  1. sanshan

    sanshan New Member

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    Hello, everyone. Two months ago I bought a used 2014 Prius from an older couple in New Mexico. But ever since I bought it, there has been this persistent odor in the car. Like a slightly musty carpet with a deteriorating adhesive/vinyl plastic/rubber smell. It is quite hard to describe. I was thinking it could be mildew in the seats, floor liner, or headliner, but I’m not sure. Doesn’t really smell like it. The car sat around a bit, but it was still driven ~5k miles annually in the last few years. It’s not completely overpowering or anything, but I would still like to have a neutral-smelling interior because otherwise the car is in excellent condition and has been very well taken care of.

    So far I have tried:
    • Replacing the cabin air filter. Big improvement as it was very musty and due for a change.
    • Using the Toyota AC system refresh foam & spray. Just masked the smell.
    • Spray with carpet cleaner solution and vacuum it up. Some improvement, but the smell eventually came back within a week.
    • Spray with Tuff Stuff, scrub, then vacuum. Same result as above.
    • Run ozone machine for 2 hrs. Zero effect.
    • Remove the rubber floor mats and carpet from the car for a week and clean them. No effect, was still as strong as with them in the car.
    • Remove the dash cover that was installed and scrape the adhesive off the dash. Mild effect? Hard to say.
    • Leave the windows cracked for the past few weeks.
    • Run my air purifier overnight twice with a carbon odor absorber. Very little effect. Still obvious when you get into the car the next morning.
    I’m running out of ideas. My plan is to just keep using carpet cleaning solution and wet vacuuming it every 2 weeks until the smell is minimized. I’m very certain the smell isn’t from the AC system. Despite all the things I listed above, the smell is 70% as strong as when I got it. I’m looking for any ideas and would appreciate any advice from you fine folks. Cheers.
     
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  2. bisco

    bisco cookie crumbler

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    congrats and welcome!

    only other thing i can think of is the hybrid battery vent tubes. they were a big problem in some gen 2's, but idk about gen 3.

    all the best!
     
  3. Grit

    Grit Senior Member

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    Run an ozone generator the car, it will kill any living organisms that’s producing foul smell.
     
  4. Mendel Leisk

    Mendel Leisk MMX GEN III

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    My usual suspect would be the AC evaporator (the AC radiator in the dash): in operation it’s cold, humidity in the incoming the air condenses on it, and if it lingers can start growing stuff. Toyota sells a kit that may help. Preventative measure is to use AC sparingly, and turn off a mile or more before destination, but continue to run fan. A pain, but works.
     
  5. BiomedO1

    BiomedO1 Senior Member

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    IMHO; you need to track down the source of the odor to eliminate it. Everything your doing above will only mask the problem for a short time.
    The most likely culprit is the HVAC system, mold in the cooling/heating coils or the car has been in a flood. A previous flood car will have mold spores in the carpet and seat, depending on how high into the interior the water got. Also check if the floor board plugs are in place and all door seals are doing it's job. The rear hatch seal can drip water into the trunk area unnoticed too.

    Hope this helps.....
     
  6. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    It's a hatchback.
    Have you checked the other end of the car?
     
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