How to remove mildew smell from a car

Step by step

1. 1

   Find the wet spot

   Take out the floor mats and press a dry paper towel into the carpet in each footwell, the trunk and under the seats. Look for water stains, damp padding or visible mold. Check whether it gets wet after rain or a car wash.

   Why: Mildew needs moisture. Water often collects under the carpet where you can't see it, and a leak keeps feeding it.

2. 2

   Fix the source of the water

   Get a leak repaired, remove anything wet that was left inside, such as gym bags, towels or spilled drinks, and wipe up condensation.

   Why: Cleaning won't last while water keeps getting in.

3. 3

   Extract and dry the carpet and pad

   Pull up as much water as possible with a wet-dry vacuum. Then dry the interior with the doors or windows open, fans blowing in, and the car parked in the sun if possible. Aim for completely dry within 24 to 48 hours.

   Why: Mold usually won't grow on materials dried that fast. Padding under car carpet holds water for a long time if left alone.

4. 4

   Clean mold off surfaces

   Wearing an N-95 and gloves, scrub visible mold off hard surfaces and mats with detergent and water, and dry them. For mildewed upholstery, vacuum, then sponge lightly with 1 cup rubbing alcohol mixed with 1 cup water after a hidden-spot test, and dry thoroughly.

   Why: Mold has to be removed, not just killed. Alcohol treats surface mildew on upholstery without soaking it.

5. 5

   Deodorize once dry

   When everything is dry, sprinkle baking soda on the carpet and seats, leave it several hours or overnight, then vacuum it up.

   Why: Baking soda absorbs the lingering musty smell after the growth is gone.

6. 6

   Air it out with fresh air

   Drive with the windows down or the ventilation on outside air, not recirculate, for the next few days.

   Why: Fresh air carries off remaining odor and helps keep the cabin dry.

Why cars get a musty smell

A car's carpet sits over thick foam padding, and the cabin is a closed space. When water gets in, from a leak, a spill, wet shoes or snow, or a window left open in the rain, it soaks into the pad, where it dries very slowly. Mold grows there and gives off the musty compounds you smell, even when the carpet surface looks dry.

That's why air fresheners don't work: the mold keeps growing underneath. EPA's rule applies in a car the same as in a house: fix the moisture, clean the mold off, and dry everything within 24 to 48 hours. See mildew smell for the science.

Mildew smell from the car AC

If the musty smell comes mainly from the vents when the AC or fan runs, and the carpet is dry, the source is probably inside the ventilation system rather than the cabin. The cleaning sources behind this page don't cover car AC systems, so have a mechanic check the system and its filter. Running the fan on outside air helps in the meantime.

For general interior care, see cleaning a car interior.

By situation

The carpet is soaked through

Extraction and fans may not be enough for a pad that's saturated. It may need lifting so the pad and floor can dry, and padding that stays moldy may need replacing.

Visible mold spots on seats or carpet

Vacuum, clean with detergent and water or the alcohol solution on upholstery, and dry fully. See mildew stains in a car for marks left behind.

Musty smell after it rained

Water is getting in. Check the footwells and trunk after the next rain to find where, and have the leak fixed.

Car stored for months

Closed-up cars can trap humidity. Air it out, check for damp, clean any growth and dry thoroughly.

What not to do

• Don't hide the smell with an air freshener. Mold keeps growing underneath, and fresheners add more chemicals to a small cabin.
• Don't leave wet mats, towels or gear in the car. They keep humidity high and feed mold.
• Don't soak the carpet when cleaning. Extra water in the pad dries slowly and creates the conditions mold needs.
• Don't run an ozone generator with anyone inside. EPA warns ozone irritates the lungs and doesn't remove odors at safe levels.

Other methods that work

Professional detailing or water-damage service

For a car that flooded or has a saturated pad, a detailer or upholstery shop can lift the carpet, dry the floor and replace padding.

Caution: Fix the leak first, or the problem returns.

Sun and airflow

Parking in the sun with windows cracked, when it's safe, helps dry the cabin and reduce mildew.

Caution: It helps drying but doesn't remove mold already growing.

Stain still there?

The smell came back after cleaning

The pad is still damp or water is still getting in. Check again after rain and dry the pad completely.

It smells worse with the heater or AC on

The ventilation system may be the source. Have it and its filter checked.

Safety

• Wear an N-95 respirator and gloves when cleaning mold, and keep the doors open while you work.
• Test alcohol and detergent on a hidden spot of upholstery first.

Never mix cleaning products; see chemicals you must never combine.

Questions

Mildew elsewhere

• Mildew: what causes it and how to remove it
• Mildew in a basement
• Mildew in carpet
• Mildew in clothes
• Mildew in the house
• Mildew in towels
• Mildew in a washing machine

Other smells in a car

• How to remove skunk smell from a car
• How to remove smoke smell from a car (cigarette smell too)
• How to remove spoiled milk smell from a car