How to Get Rid of a Musty or Mildew Smell in Your Car (Step by Step)

To get rid of a musty or mildew smell in your car, you have to find the moisture, dry it completely, and clean what it soaked into. Air fresheners won't work, because the smell comes from mildew growing in damp carpet padding, seat foam, the cabin air filter, or the A/C system. Remove the source and the smell goes with it.

Here's the process, step by step.

Press your hand hard into the carpet and feel for dampness. Check these spots, which are where water usually hides:

• •Under the floor mats, especially the driver's side and rear footwells
• •Under the front seats, where spilled drinks run down and sit
• •The trunk and spare tire well. Lift the trunk floor. Water often pools here from a bad trunk seal
• •Below the windshield and A-pillars, a sign of a leaking windshield seal or clogged cowl drain
• •Around the sunroof. Sunroofs have drain tubes in the corners that clog with debris and overflow into the headliner and carpet
• •The passenger footwell. A clogged A/C drain can back up condensation here

If the smell is strongest when the A/C first turns on, the source is probably the cabin air filter or the A/C evaporator, not the carpet. Skip ahead to Step 4.

If you find wet carpet and haven't spilled anything, water is getting in somewhere. Cleaning won't last until the leak is fixed. Common fixes:

• •Clear the sunroof drains with compressed air or a length of trimmer line
• •Clear leaves and debris from the cowl at the base of the windshield
• •Replace a cracked door or trunk weatherstrip
• •Have a windshield shop check the seal if water is coming in at the glass

This is the step most people rush, and it's the most important one. Mildew can only grow where there's moisture.

1. 1.Pull out the floor mats and dry them separately in the sun
2. 2.Open all the doors on a dry, sunny day and let the cabin air out for several hours
3. 3.Pull water out of soaked carpet with a wet/dry shop vac. Press the nozzle down hard and go slowly
4. 4.Point a fan at damp areas, or run a small dehumidifier inside the car with the windows cracked
5. 5.Use moisture absorbers (the calcium chloride tubs sold for closets) for a few days afterward if the car stays damp

Carpet can feel dry on top while the foam padding underneath is still wet. Give it more time than you think it needs.

For carpet and seats: Vacuum thoroughly, then clean with an enzyme-based carpet and upholstery cleaner made for odors. A solution of equal parts white vinegar and water also works on carpet, but test a hidden spot first and never use it on leather. Agitate with a stiff brush, then extract with the wet/dry vac or a carpet extractor. Use as little water as possible, and dry again afterward.

For hard surfaces: Wipe door pockets, seat tracks, and cup holders with an interior cleaner. Mildew grows in these spots too.

For the cabin air filter: Replace it. It's usually behind the glovebox and takes ten minutes. A damp, dirty filter blows a musty smell through every vent.

For the A/C system: Use an A/C evaporator foam cleaner from an auto parts store, following its directions. If the smell continues, a mechanic can clean the evaporator directly.

Once everything is dry and clean:

• •Sprinkle baking soda on the carpet, let it sit overnight, then vacuum it up
• •Leave activated charcoal bags under the seats for a week or two. They absorb odor instead of covering it

Ozone generators are sold for this, but use caution. Ozone is harmful to breathe, can dry out rubber and plastic with heavy use, and only works after the moisture is gone. If you use one, the car must be empty with the doors shut, then aired out fully before anyone gets in.

• •Turn off the A/C a few minutes before you park and let the fan run. That dries the evaporator so mildew can't grow
• •Don't leave wet towels, gym clothes, or umbrellas in the car
• •Use rubber floor mats during the rainy season
• •Clean spills right away, including what soaks into the carpet, not just what's on top
• •Replace the cabin air filter about once a year

Mildew in a car mostly causes the smell, but mold spores can bother people with allergies or asthma. If you see visible mold spread across seats, carpet, or the headliner, wear gloves and an N95 mask while cleaning. Or leave it to a professional who can extract and steam-clean the cabin properly.

If the carpet padding has been wet for a long time, home tools usually can't pull enough moisture out. Our Gold Detail includes hot water shampoo extraction of all carpets and seats plus steam cleaning of hard surfaces, which gets to the source of the smell. For more on what causes musty smells, see why your car smells musty.

Book online or call (310) 692-4495.