How to Remove Musty Odors From a Car Cover (Without Ruining the Fabric)

ByDaniel Brooks Car Cover

⚡ Quick Answer

To remove musty odors from a car cover, hose off loose dirt, then soak the cover in warm water with an oxygen-based cleaner or mild detergent. Scrub musty spots with a soft brush, rinse until no suds remain, and dry it flat in direct sunlight. Full drying is what stops the smell from coming back.

Steps to remove the smell

  1. 1
    Shake out the cover and hose down both sides
  2. 2
    Soak it in warm water and an oxygen cleaner for 1-2 hours
  3. 3
    Rinse fully, then dry flat in direct sun

Mistakes that bring the smell back

  • ✓
    Using chlorine bleach on a coated cover
  • ✓
    Folding the cover away while still damp
  • ✓
    Spraying air freshener instead of washing it

You pull the cover off your car and a sour, damp smell rolls out before you’ve even finished folding it back. It clings to your hands. It fills the garage. And spraying it with air freshener only masks the problem for an hour.

This musty smell almost always means mold or mildew spores have taken hold somewhere in the fabric. Michael has seen this happen to brand-new covers stored in a closed garage for just one humid week. The good news is that you can usually fix it yourself, without buying a new cover.

Below is the exact process for washing the smell out, plus how to stop it from showing up again.

📌 Key Takeaways

  • →
    Musty smell means moisture. It’s a sign of mold or mildew growing in the fibers, not just dust.
  • →
    Soaking beats spraying. A full soak removes the odor source. A spray only covers it up.
  • →
    Sunlight is free disinfectant. UV light and heat kill mold spores and dry the fabric fast.
  • →
    Bleach can ruin coatings. Chlorine bleach strips the water-repellent finish on most covers.
  • →
    Storage causes repeat smells. A cover folded away even slightly damp will smell musty again within days.

Why Does a Car Cover Smell Musty?

A car cover smells musty because moisture got trapped against the fabric long enough for mold or mildew to grow. You already know mold needs damp, dark conditions. What you might not know is that the cover itself can create those conditions, even when the weather outside is dry.

Condensation can form underneath the cover overnight, especially if you covered the car before the paint and glass had fully cooled. That moisture sits against the fabric with little airflow. Add a closed garage, and you’ve built a small greenhouse for mold spores.

Here’s the surprising part: the storage bag is often the real culprit, not the weather. A cover folded into a sealed plastic tote while even slightly damp will mildew faster than one left outside in light rain, simply because there’s no air movement to dry it out.

So if you’re dealing with a musty car cover, the fabric was wet at some point and didn’t dry fast enough. The EPA’s guidance on mold cleanup backs this up: moisture control, not just cleaning, is the key to making mold problems go away for good.

What You’ll Need to Clean a Musty Car Cover

Gather everything first so you’re not running back and forth mid-wash. Most of this is already in your garage.

📋 Supplies for washing a musty car cover


  • A large tub, bathtub, or kiddie pool: Big enough to fully submerge the cover.

  • Mild detergent or an oxygen-based cleaner: Targets odor at the source instead of masking it.

  • A soft-bristle brush: For scrubbing musty spots without damaging the weave.

  • A flat, sunny spot or clothesline: A driveway, deck, or fence works well.

How to Wash a Musty Car Cover, Step by Step

Wash the whole cover, not just the smelly section. Mold spores spread, so a spot-clean rarely solves the problem for long. Follow these steps in order.

🔢 Step-by-Step: Washing Out a Musty Car Cover

  1. 1

    Shake out loose dirt and debris

    Do this outside. Leaves, dust, and pollen feed mold and make the smell worse over time.

  2. 2

    Hose down both sides

    Rinse the inside and outside to loosen grime before it sits in the cleaning solution.

  3. 3

    Soak in warm water and cleaner

    Mix a mild detergent or oxygen-based cleaner into warm water. Submerge the cover for 1-2 hours.

  4. 4

    Scrub the musty spots

    Use the soft brush in small circles on any discolored or strong-smelling areas.

  5. 5

    Rinse until no suds remain

    Leftover detergent attracts dirt and can leave a faint smell of its own.

  6. ✓

    Dry it flat in direct sunlight

    Lay it over a fence, railing, or clothesline. Full sun and air movement finish the job.

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How to Get Rid of the Mildew Smell for Good

If the smell lingers after one wash, the mold likely worked deep into the fibers. A second round with a stronger approach usually finishes it off.

Try a soak in a mix of one part white vinegar to four parts warm water for 30 minutes before your regular wash. Vinegar’s acidity breaks down mildew that detergent alone can miss. Rinse well afterward so the vinegar smell doesn’t linger either.

Baking soda works as a gentler backup. Sprinkle it dry over damp trouble spots, let it sit for a few hours, then brush it off before washing. It absorbs odor instead of just covering it.

⚠️ Warning

Skip chlorine bleach. Most car covers have a water-repellent or UV-resistant coating, and bleach breaks that coating down. You’ll trade the musty smell for a cover that soaks through in the next rainstorm.

What Most People Get Wrong About Cleaning a Car Cover

A few common habits explain why the smell keeps coming back, even after a wash.

Spraying air freshener on it. A fragrance spray covers the smell for a short time, but it doesn’t touch the mold underneath. The musty odor returns as soon as the scent fades.

Tossing it in the clothes dryer. High heat can warp the elastic hem and break down waterproof coatings. Most cover manufacturers list air-drying only, for good reason.

Assuming a quick rinse is enough. Mold sits down in the fibers, not just on the surface. A rinse without soap or soak time mostly just spreads it around.

How to Keep a Car Cover From Smelling Musty Again

Cleaning the cover only solves half the problem. If you store it the same way again, the smell comes back within a couple of weeks. Prevention comes down to one thing: never store it wet.

✅ Tip

Toss a moisture-absorbing packet or a small box of baking soda into the storage bag with the cover. It keeps humidity down even if the garage itself runs damp.

Keep a few habits in mind between washes:

  • Let the cover air out for at least an hour before folding it away, even if it looks dry.
  • Store it in a breathable bag, not sealed plastic, so any trapped moisture can escape.
  • Check on it every few weeks during long-term storage, especially in humid climates.
  • Keep indoor storage humidity below 60% where you can, since that’s the threshold most mold needs to spread.

So if your garage runs damp through certain seasons, that prevention step matters more than any cleaner you use.

The Bottom Line

A musty car cover almost always means trapped moisture, not a ruined cover. Wash it fully, dry it completely in the sun, and store it dry, and the smell won’t return.

One thing to do right now: go check the cover in storage. If it’s even slightly damp, pull it out and let it air dry before the smell has a chance to set in.

Frequently Asked Questions

Can I put a car cover in the washing machine?

Many fabric car covers can go in a large-capacity washer on a gentle, cold cycle without spin-dry. Check the care tag first, since some coated or fitted covers are hand-wash only to protect the coating.

Will vinegar get mildew smell out of a car cover?

Yes. A 1-to-4 mix of white vinegar and warm water breaks down mildew odor effectively. Soak for 30 minutes, then wash and rinse well so no vinegar scent lingers behind.

Why does my car cover smell musty again after washing?

It was likely folded away before it fully dried. Any trapped dampness lets mold restart within days. Always confirm the cover is bone-dry, inside and out, before storing it.

Can I use bleach on a car cover?

It’s best to avoid it. Chlorine bleach weakens the water-repellent and UV coatings on most covers, which can lead to leaking or sun damage. An oxygen-based cleaner or diluted vinegar is a safer choice.

How long does a car cover take to air dry?

In direct sun with good airflow, most covers dry in 2 to 4 hours. Thicker, multi-layer covers can take closer to a full day. Always check the inside seams, since they trap moisture longest.

Does sunlight kill mold on fabric?

Yes. UV light and heat from direct sun kill many mold spores on the surface and speed up drying, which removes the moisture mold needs to keep growing. It works best alongside washing, not as a stand-alone fix.

Should I store a car cover in a plastic bag?

No. Sealed plastic traps any leftover moisture against the fabric. Use a breathable bag, such as the cotton or mesh storage sack many covers ship with, or even a pillowcase.

This article covers general fabric-care steps. Always follow your specific car cover manufacturer’s care instructions, since materials and coatings vary by brand.