Fungus and mold grow in your car when moisture gets trapped inside, usually from wet floors, damp upholstery, or a leaking window seal

The most common places fungus appears are under floor mats, inside the air vents, on the dashboard, and in the trunk. You can usually spot it as black or green spots, a fuzzy coating, or a musty smell that won't go away even after you air out the car. Fungus thrives in darkness and humidity, so a car that sits unused or has poor ventilation becomes a breeding ground quickly.

Removing it requires three steps: drying out the interior, cleaning the affected surfaces, and preventing it from coming back. The method you use depends on how much fungus is present and where it's located. A small patch on a floor mat is a quick fix; fungus inside the air conditioning system requires more work.

Key Takeaways

  • Fungus grows in cars because of trapped moisture, usually from wet carpets, leaking seals, or poor ventilation.
  • You can remove surface fungus with a vacuum, damp cloth, and white vinegar or a commercial antifungal cleaner.
  • Fungus inside air vents and the air conditioning system requires running the AC on high heat with the windows up, or having a professional clean the system.
  • Preventing fungus means keeping the interior dry, cracking windows when parked, and leaving the car in sunlight when possible.
  • If the smell persists after cleaning, the fungus is likely in the ventilation system and you may need professional treatment.

Dry out the interior completely before cleaning

Moisture is what keeps fungus alive, so your first step is to remove as much water as possible from the car. Open all the doors and windows and leave them open for at least 24 hours, longer if the weather is dry and warm. If it's raining or humid outside, wait for a clear day or use the car's heating system instead.

Remove the floor mats and any removable carpets and lay them outside in direct sunlight. Sunlight kills fungus naturally. If the seats or carpets are visibly wet, use a wet/dry vacuum to pull water out of the fabric. Run the vacuum over the floor, under the seats, and inside the trunk. Then turn on the car's heating system to full heat with the windows down for 15 to 20 minutes to drive moisture out through the vents.

If the interior is very damp or the car has been sitting closed for weeks, place open containers of baking soda or activated charcoal inside overnight. These absorb moisture and odors. Leave the car parked in direct sunlight during the day if you can; heat and UV light both kill fungus and dry out the space faster.

Clean visible fungus with vinegar or antifungal spray

Once the interior is dry, tackle the visible spots. For small patches on hard surfaces like the dashboard or door panels, mix equal parts white vinegar and water in a spray bottle. Spray the affected area and wipe it with a clean cloth. Vinegar kills fungus on contact and the smell fades as it dries. For stubborn spots, let the vinegar sit for 10 minutes before wiping.

For fabric surfaces like seats or carpets, spray the vinegar solution lightly—do not soak the fabric—and wipe with a cloth. You can also use a commercial antifungal cleaner made for cars; follow the product instructions for how long to let it sit before wiping. Avoid bleach on fabric because it can damage the material and leave stains.

If fungus is on the floor mats, scrub them with a stiff brush and the vinegar solution, then rinse with clean water and let them dry completely in the sun before putting them back in the car. Check under the mats for fungus on the floor itself; if you find it, spray and wipe that area too, then leave it uncovered to dry.

Clean the air vents and ventilation system

Fungus inside the air vents and air conditioning system is harder to reach but causes the musty smell that lingers even after you clean the visible surfaces. The fastest way to kill it is to run the car's air conditioning on the highest heat setting with all windows closed for 15 to 20 minutes. The heat dries out the vents and kills fungus growing there.

For a deeper clean, use a commercial air vent cleaner. These come as aerosol sprays that you spray directly into the air intake vents while the car is running. Follow the product instructions for how long to run the system after spraying. Some products require you to spray into the vents on the dashboard; others go into the intake near the windshield.

If the smell persists after you clean the vents yourself, the fungus is likely deep inside the air conditioning evaporator, which sits behind the dashboard. This requires professional cleaning. A technician will use specialized equipment to spray antifungal solution through the AC system. This costs between $150 and $400 depending on your car and the service, but it's the only way to fully clean the system from the inside.

Find and fix the source of moisture

Fungus will come back if you don't stop moisture from getting into the car. Check for leaks around the windows, door seals, and the trunk. Roll down each window and look at the rubber seal; if it's cracked or loose, water is getting in. Press on the door seals to feel if they're still flexible or if they've hardened and shrunk away from the frame.

If you find a leak, you can temporarily seal it with weatherstripping tape from an auto parts store. Cut the tape to length and press it firmly into the gap. This is a temporary fix; a permanent repair usually requires replacing the seal, which a mechanic can do. Check the trunk seal the same way—open the trunk and look at the rubber gasket around the edge. If it's damaged, water will pool inside after rain.

Also check under the car for standing water after it rains. If water collects under the floor mats, there may be a drain hole that's clogged. Most cars have small drain holes in the floor to let water out; if these are blocked by dirt or debris, water sits inside and fungus grows. You can often clear them by poking a thin wire or straightened coat hanger through the hole from underneath the car.

Prevent fungus from growing back

Once you've cleaned the fungus, keep it from returning by managing moisture. Crack the windows slightly when you park the car, even in light rain. This lets air circulate and prevents the interior from becoming a closed, humid box. If you park in a garage, leave the windows cracked unless it's very cold outside.

Park in direct sunlight when you can. UV light and heat kill fungus spores and dry out the interior naturally. If you park in a shaded spot or garage most of the time, try to move the car into the sun at least once a week for a few hours.

After driving in heavy rain or washing the car, leave the doors and windows open for 30 minutes to an hour to let moisture escape. Wipe down wet seats and floor mats with a dry cloth. If you spill liquid inside the car, clean it up when ready and dry the area with a cloth or paper towels; don't let it sit.

Keep an open container of baking soda or activated charcoal inside the car at all times, especially if you live in a humid climate. Replace it every month or two. This absorbs moisture and odors before fungus has a chance to grow. You can also buy small silica gel packets made for cars and place them under the seats.

When to seek professional help

If the musty smell returns within a few weeks of cleaning, or if you see fungus reappear in the same spots, the problem is likely in the air conditioning system or there's a moisture source you haven't found yet. A mechanic can inspect the seals, check for leaks, and clean the AC system professionally.

If fungus has spread to the insulation under the carpet or inside the door panels, it may be too deep to clean yourself. This is rare but can happen if the car has been flooded or sat with water inside for a long time. A professional detailer or mechanic can assess whether the damage requires replacing parts or if cleaning will solve it.

Frequently Asked Questions

Is the musty smell dangerous to breathe?

Fungus spores in the air can trigger allergies or asthma in some people, especially with prolonged exposure. The smell itself isn't toxic, but it's a sign that fungus is actively growing. Clean it out and fix the moisture problem to stop spores from building up inside the car.

Can I use bleach to kill fungus in my car?

Bleach kills fungus but can damage car upholstery, plastic, and paint. Use white vinegar or a commercial antifungal cleaner instead. If you do use bleach, dilute it heavily (one part bleach to ten parts water), test it on a hidden area first, and rinse thoroughly with clean water afterward.

How long does it take to get rid of the smell?

Surface cleaning removes the smell in a few days if the fungus is only on visible surfaces. If the smell lingers after a week, the fungus is in the ventilation system and requires professional cleaning or repeated treatments with air vent cleaner.

Will opening the windows while driving help remove fungus?

Yes. Driving with the windows down increases air circulation and helps dry out the interior. Combine this with running the heat on high to speed up the drying process. Do this for 15 to 20 minutes on a clear day.

Can fungus damage the car's structure or engine?

Fungus grows on surfaces where moisture collects—carpets, upholstery, and vents—not on the engine or structural parts. However, if water is leaking into the car in large amounts, it can damage electrical systems and cause rust. Fix any leaks as soon as you find them.