Car mold or mildew odor diagnosis & cure procedure:
This article explains how to get rid of mold, mildew, or musty odors in cars, trucks, campers, boats, and similar vehicles.
We discuss the diagnosis of the cause of moldy or "mildewey" smells in cars and other vehicles, how to track down the odor to its source, how to clean or remove the problem, and the importance of finding and fixing the leak that caused the smell in the first place.
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This article explains the causes and cures of moldy, musty or "mildew" smells in cars or similar vehicles, and how best to get rid of the offensive, unhealthy, or unsafe as well as obnoxious moldy odor.
The photos above and at left show a nearly-new car that developed an unbearable mold smell traced to leaks at the passenger side window pillar.
Even though mold was not visible in the car interior and little mold was found in air and vacuum tests of the accessible vehicle surfaces, MVOCs from mold contamination in the leak area had produced a very strong musty "mildew" (actually mold) smell that required extensive cleaning and some material replacement to make the vehicle usable.
Details of this successful car deodorization process are included in this article.
Mold growth in a vehicle such as a boat, camper, car, or truck can be hard to see but easy to smell, producing an obnoxious moldy or musty smell that some owners refer to as car "mildew". Usually a moldy smelling car that stinks as soon as you open a door to enter it, with the engine off, is due to a water leak and mold contaminated soft goods such as sound insulation, carpets, or even seats or the head liner. Don't forget to check the trunk for leaks and moldy smell sources too.
A moldy smell "mildew smell" coming out of the heating/cooling vents may be associated with mold growth inside the A/C evaporator itself according to Car Talk whose hosts suggested trying to "kill" the mold with Lysol spray. In general we need to clean up or remove mold from problem areas; killing mold is ineffective, incomplete, and may leave harmful particles that continue to plague the car's occupants respiratory systems. See MOLD KILLING GUIDE for details about attempts to kill mold in buildings - it also applies to cars. .
What you are actually smelling if you report a "moldy odor" is not necessarily air containing mold spores. You may be smelling MVOCs, gases produced by some mold species under some conditions. If we smell mold, is mold present and is that a problem? Most people have a pretty good idea of moldy or musty smell as associated with mold. If you smell mold or find it at important levels in screening samples of air, dust, or vacuumed surfaces, (by quantity or by particle type in samples) it is probably there.
Or it was there. The moldy smell may persist even after the actual mold reservoir has been removed. That's because the volatile MVOC gases may have penetrated and been absorbed into other soft goods (car seats, headliner, carpeting) even if those items were not themselves ever wet or mold contaminated.
MVOCs themselves can be a respiratory irritant and might even be toxic to some individuals. We discuss MVOCs in more detail in our building hazards section at Mold Odors - MVOCs.
A moldy car is more than an obnoxious-smelling vehicle in which to travel. For occupants who are at extra risk of respiratory or health problems such as asthmatics, elderly, infant, or immune-compromised people, exposure to high levels of mold, or of mold smells (MVOCs or mold volatile organic compounds) may be affected even when there is no actual visible mold.
There are lots of clues that can help identify and protect you from buying a vehicle that has been flooded. Just below are some flooded car inspection highlights. See FLOODED CAR DETECTION for complete details on how to inspect a car to detect prior flood or water damage: 
The cost of successfully removing a moldy smell from a car ranges from low if you found and fixed a small problem early (wet smelly floor mats) to very high if the smell contamination is extensive and involves extensive car interior materials such as the seating and head liner.
If the vehicle interior is visibly moldy throughout, the car is, in our experience, likely to be a total loss. This is certainly likely to be the case for a car that has been under water, such as in a flood zone or hurricane. Don't get fooled into accepting a superficial "clean-up" job on such a vehicle.
The most reliable to find and remove the source and cause of a moldy smell in a vehicle involves several steps. We list the car deodorizing steps, and following the list we discuss each of these car smell cure steps in more detail.
These car mold removal steps are discussed in detail below.
Most people are pretty accurate in recognizing a musty, "mildew" odor or moldy odor indoors or inside of a car. To be technically accurate, mildew, a smaller group of mold types, grows only on living plants and not in cars. If it smells moldy, it's mold (not mildew).
But because tackling a moldy car smell can be difficult, expensive, and frustrating, it would be smart to be sure we're fighting the right battle before beginning to tear the boat, car, camper, or truck apart to find and get rid of moldy materials.
To confirm that the smell is indeed coming from inside the car, and that it's a moldy smell, begin with the car with engine off, the vehicle washed clean, including the under-carriage, (you weren't out driving through a manure-covered barnyard first were you?).
Should you test your car for toxic mold contamination? No. Not normally. Smelling and looking for mold in a vehicle should be sufficient, and you would not normally need to actually test a car for toxic or allergenic mold contamination.
In our photo (left) you can see our field test kit for mold at the smelly-car's rear corner. For the owners, we performed a series of pro-bono mold tests on this moldy-smelling car in preparing this article.
We tested the vehicle air for abnormal levels of airborne mold and we collected vacuum samples of dust from the vehicle's carpets and padding to look for evidence of problem mold contamination. We did not need to test for MVOCs - smelling the car was enough.
Our mold test lab photos (below) show examples of what we found in our carpet dust samples from this moldy-smelling car: dog hair, dog dander, cat dander (see CAT DANDER in BUILDINGS for a general discussion about pet allergies and dander), dust mite fecal pellets, road dust and dirt, incidental plant fragments, and occasional typical outdoor airborne mold spores. We also found a some starch granules and some yeast cells, possibly associated with food spillage. There was no significant visible mold spore contamination in the sampled areas.
The contamination was by a moldy smell - MVOCs from mold that more likely had occupied harder-to reach areas under the dashboard.
How to smell-test a car for mold: Close all of the vehicle windows, doors, hatches.
Let the vehicle sit in the sunlight until its interior is warm. On a summer day this may require just a half hour or so.
Select your smell-test person, someone who is particularly sensitive to mold, such as your wife or girl friend. (Make sure she's not one of the at-risk people we've described above.) Women usually have a keener sense of smell than men, and we have found that pregnant women sometimes have an extremely sensitive ability to detect odors. However we think that exposing pregnant women to possibly moldy cars or any other obnoxious stuff is a not good idea.
Have the smell test person approach the car, breathing normally. Starting with the door closest to where you already think the mold smell is strongest, open the door, quickly slide into the seat, and close the door.
Take a whiff of the smelly car interior. Get out of the car and close the door again.
Report the results: did the car smell moldy? How bad was it?
If your smelly vehicle is an RV, camper, or boat, check that the moldy odor source is not coming from an indirect source such as a moldy boat cover or RV cover. If your boat or RV cover contains plastic or vinyl, see VINYL SIDING or WINDOW PLASTIC ODORS as an example of that material as a potential odor source in buildings; odors from hot vinyl in cars are a similar phenomenon..
Parking a vehicle in a smelly area, over manure or over a dead animal, or covering a vehicle with a moldy canvas or vinyl car cover are examples of indirect car smell sources.
Other examples of tracking down indirect odor sources are provided at DUCT & AIR HANDLER ODORS (duct work picking up and transporting odors from one place to another in a building - this can happen in a car too),
and at ODOR DIAGNOSIS CHECKLIST, PROCEDURE - our list of steps to track down a smell in a building. Some of the strategy discussed there, such as noticing the time of day, weather conditions, etc. may help track down a smell in a car.
Our photo (left) shows the peeled-back floor carpeting in the moldy-smelling car's front passenger area. The car was nearly new and things looked clean, but carpeting, padding, and sound insulation extending up under the dashboard had been wet in this area - the primary odor reservoir in this vehicle.
If necessary, have the smell-tester repeat this procedure for the other car seats and doors, waiting five or ten minutes in fresh air between each test.
Beware: your test results can be thrown off: repeated or prolonged exposure to a moldy smell makes many people become less sensitive to the odor, potentially making their report unreliable if the smeller does not wait long enough in fresh air between smell-tests of the vehicle.
If necessary, use our SMELL PATCH TEST to confirm that the odor source is a specific item such as car carpeting, sound insulation, seat, or headliner.
Our photo (left) shows how we create a smell patch test to isolate odors to a specific area or material.
Foil is taped over a clean folded paper towel placed on the test surface, left for 24 hours, then rapidly removed, the towel is balled in the foil, and the assembly is quickly taken outside into fresh air for a sniff test to compare the level of smell from different areas.
This procedure is often very accurate at pinpointing smell to a particular surface. Details are at SMELL PATCH TEST to FIND ODOR SOURCE.
It is essential to find and cure the cause of a moldy smell in a vehicle - otherwise the entire diagnostic, cleaning, and testing process will be wasted.
In the moldy car case used as an example in this article, a water leak at the front passenger side windshield pillar was sending water down inside the pillar into the area behind and under the dash board on the passenger side, ultimately onto the passenger side floor.
The car's owners first noticed the leak problem as a wet floor mat. On exploring they found that carpeting below the floor mat was still more wet. This meant trouble.
In our photo (left) the author points to the very origin of the roof and windshield pillar leak on the car's passenger side.The dealer was able to trace the leak to its source, and the leak was repaired. But the moldy smell remained.
Getting rid of a moldy smell in a vehicle means first, removing the wet or moldy materials that are the home of the stink. The proper approach to cleaning out a mold problem is to remove the mold. Approaches that focus on "mold killers" or mold deodorants are ineffective.
But how much smelly, moldy, or previously wet material needs to be removed? We did not have to remove the rear carpets in this case.
Our photos (above) show the inspection of rear carpeting where it terminated under the front passenger seat. We looked for evidence of wetness having extended back to the rear floor of the car, such as moisture or stains. Remember that if you are checking for leaks and moisture in dry weather, the wet carpeting may have dried out and may look just fine. Smell it and look for water stains.
Carpeting, seats, sound insulation, head liners, door liners, or other vehicle materials that have actually been soaked and that smell moldy need to be removed and disposed-of, and the exposed surfaces of the vehicle cleaned using conventional cleaners (soap and water would be fine).
Our photo (left) shows the primary smell reservoir in this mold-stinky car: the carpet padding and sound insulation material. A topic of considerable discussion was just how much of this padding to remove.
Ideally all of the padding that had been wet would have been pulled from the car. The problem, explained by the car dealer, was that that this padding extends up under the dashboard, higher than can be readily pulled out from inside the car, unless the entire dashboard assembly is first removed.
Our opinion and possibly that of car experts Click and Clack the Tappet Brothers (NPR) is that we do not ever want to have the dealer remove the car's dashboard if we can possibly avoid it. Too often wires and connections are not properly restored, and electrical, control, and maybe other problems may plague the car for the rest of its life. The owners heeded this advice and compromised on the mold deodorizing process. Sound insulation was pulled out and removed completely, for "as far as the dealer's service tech could reach" without removing the dashboard.
The decision, which is one with which we agree, to leave the dash board in place might explain why after all the removal of smelly padding and carpeting, it took quite some time for the remaining moldy odor to nearly disappear from the car.
Nearby porous materials such as the vehicle's head liner that were never wet but that have been exposed to moldy odors may continue to smell even after the original smell source has been cleaned.
Sometimes, a combination of cleaning, sun-cooking with windows open, and the passage of time will dissipate the remaining MVOC-related moldy smell from these secondary smell reservoirs, enough that the vehicle is usable. If not, additional materials may need to be removed.
Two additional moldy car smell deodorizing steps are described next.
Generally we do not recommend car deodorants - they only cover up the smell, the do not get rid of the source. It will be back.
Ozone generators produce ozone gas, a strong oxidant (and dangerous to breathe) that temporarily fills the car interior to try to "oxidize" or "kill" mold that your car cleaning company couldn't reach - such as sound insulation padding up high inside the front fire-wall of the car, under the dash board.
Watch out: Be very careful if you're going to permit someone to ozone-treat your car. If the ozone treatment is over-done, the ozone can oxidize other car materials, causing a more horrible odor than ever. Details about over-dosing with ozone are found at OZONE MOLD / ODOR TREATMENT WARNINGS.
I took my automobile to a Chrysler dealer to have the evaporator (AC vent system ) cleaned due to a bacteria/mold smell which I was told is common in Chrysler products.
The dealer used a chemical “cleaner” which on the market which was supposed to remove this material. It apparently worked however I was left with a terrible perfume-like odor that would not go away.
This went on for a few weeks until they finally had a company come in and ozone treat the interior.
I need to point out I have severe emphysema and asthma.
The individuals there at the dealership including the service man from the company all said the equipment was used “over the weekend” for an extended period of time to remove the perfume smell and allowed to run over the weekend.
They used 2 ozone generators inside the car: one in the trunk and one in the interior cabin area.
The “expert” from the cleaning company said what he smells is “CLEAN AIR” – MY REPLY IS SIMPLY BULL.
NOW I have a serious odd “chemical odor” in the car which is more (and then some) irritating than the perfume odor. This smell has now persisted for over 30 days now with the car left running with the AC and fans running, sitting in an open area with the windows down and so on, they even cleaned the upholstery and rugs.
Question is what the dickens is going on?
Is my car ruined due to ozone treatment?
Has a chemical reaction started or occurred? And most significant is this dangerous? I need to get rid of the Auto but cannot dump a car on someone that may he harmed by this odor!
Please advise me about what has happened here! - M.R.
OPINION: With just an email naturally no one can accurately diagnose nor cure an odor problem nor really assess its level of risk, but here are some thoughts based on our experience and your report:
What you describe does not sound like the most effective approach to a car odor and worse, as if it has indeed made things worse. We can only guess from so little info, but
These reasons are why, even though it sounds like a lot more trouble, it is actually often more effective and less expensive to find and remove the original odor source in the first place, along with finding and fixing its cause.
Now, we are afraid, it may be too late for this car and it might have been rendered unusable. And we agree that what you smell is certainly not "clean air" - if the air in the car were clean - odor free - it would not smell.
Before giving up on the overdosed, over-ozoned car, you can try the next suggestion we list below:
Air out the car and let it bake in the sun with its windows open (and watch out for rainstorms). Otherwise, to restore the car now may require identifying just what in-car components are smell sources, they have to then be removed, the car aired-out, and new materials installed. These might include:
We do not advise just passing on the car to someone else before these problems are fixed - you wouldn't want to be responsible for some future car-occupant's health or respiratory problem that might be caused, contributed to, or blamed-on the smelly car.
On warm, dry days, with the vehicle's windows open, or if it's a boat, with any covers removed, expose the vehicle to full days of sunlight and fresh air.
In the moldy car case used as an example in this article, a combination of removal of smelly carpeting and sound insulation from the front of the vehicle, combined with cleaning and deodorizing, left the car with a slight moldy odor that we could just barely detect eight months after the cleanup began.
The owners were satisfied.
If the vehicle still smells as moldy as before, you have not found the source and you'll need to be more aggressive in finding and removing smell-contaminated materials. Go back to step 1.
Also see CAR SMELL & ODOR Diagnosis
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Hi, I love your site and can often spend hours on it gaining valuable honest and accurate information. I need your help as I am going crazy over a car I purchased for my son. I flew to Iowa and spent every penny I had to buy him the car he always wanted. I drove it home 1000 miles to Mahopac NY. I had to stop many times for fresh air as my eyes were burning and I felt sick.
The previous owner denies any problems with the car and denies any cleaning treatments or ozone. Of course he does. This is a 2007 Chevy Monte Carlo with 3000 miles stored in a heated barn surrounded by 100's of acres of corn or soy fields. The carpet has a moldy smell. The vents have a moldy smell. The seats have a chemical odor. I needed to throw away my clothing after unsuccessfully washing three times. The seat belts and seats have white mold stains when looking across the face of them. The jute padding smelled of mildew. The butyl tape used to seal holes smells like death burned over?
I have stripped the car down to the steering column being the only remaining object in the car. I have covered almost every inch with dynamat to block out odors. I still get a sweet odor coming from the chassis opening for the seat belts. This is the same odor that contaminated the interior insulator attached to the front fire wall.
All of the hoses in the car interior or engine have a white powder substance inside them. I found a 1" pattern of growth behind a headlight that I wiped off already. The best way to describe it was almost Braille like formation, as in reading for the blind. I don't know if this car suffered from aerial pesticide overspray, crop harvesting dust, ozone, chemical clean up? I don't want my son to get sick from this car and the only way I will be able to sleep is if I get some of these things tested. Can you please help?
I notice you are in PK and I could easily drop off some of the suspect items for your testing. I realize there will be a cost for your service. Thanks - Jason
I'm sorry to read about your aggravation with the car, Jason, and will offer what I can to assist. Given your strong conviction that there is a mold problem in the car I'm not sure that further testing is the place to start. If there is a mold smell in a car it is very difficult or even impossible to remove without
Speculating: If the car was previously exposed to flooding it may have been condemned and disposed-of, then sold improperly on the market. If so, fraud may have been involved in its sale to you. I recommend some checking up based on the vehicle VIN to review its history. If the car was flooded you may want to consider returning it to the seller for a full refund.
Another source of car odors can be trouble with the heating and A/C systems, and leaks into that system ductwork. That's not itself a mold issue.
If it's a mold contamination problem, the alternative, which could be costly, is to track down odors in the car to sources that you haven't found and replace those materials. See SMELL PATCH TEST to FIND ODOR SOURCE.
I was hoping you might be able to advise me here. I just got an ozone shock treatment done to my car. There is a strong chemical residue smell that has lingered now going on four days. I’ve left my windows open all day for he past four days except during the night to no avail. I read on your website that the ozone treatment can create chemical odors if it is overdone. I believe that is what happened to me. Will the smell ever go away? Thanks. - M.R.
A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem with when, how, where, and for how long your car was zapped with ozone.
That said, I'm sorry to say that we have received a number of car owner complaints about horrible odors that persist post-ozone treatment of cars and homes.
It appears that over-use or overexposure in level or time during an ozone treatment for "odors" or "mold" (fundamentally a flawed approach and one not recommended by authorities and experts), there may have been oxidation of plastics or other materials that can leave a persistent and unpleasant smell. (Also see VINYL SIDING or WINDOW PLASTIC ODORS)
In some cases I've followed, after months of airing-out of the smelly car on sunny days with windows open, the smell level dropped to acceptable. In others, after months, owners resorted to stripping out all insulation, carpeting, headliners, seats, even dashboard components, to try to remove the offending odor and salvage the car (SMELL PATCH TEST to FIND ODOR SOURCE can help pinpoint an odor source in a car such as the headliner, carpets, seating). Some abandoned the vehicle.
Before trying anything drastic I would
My vehicle had a defective door seal and it allowed water to get inside the vehicle. The dealership fixed the seal and placed an ozonator inside the vehicle for 72 hours.
The vehicle now has a horrible smell and it's less that a year old. It has been to the dealership three additional times but they are unable to fix it. Is there any way that I can measure the oxidation level of the vehicle's interior to determine if it is harmful? - P.D. 2015, Jan 19
The odor you smell following an ozone overdose-treatment of a car is typically the result of oxidation of various plastics in the vehicle, most certainly some more than others.
You could order an air test that uses a vacuum cylinder to capture gases from the vehicle and then characterize them but in my OPINION that is not cost justified: a reliable test properly conducted is likely to cost more than $1000. USD and still won't support an unequivocal answer to possible health hazards as exposure levels vary.
Also in my opinion it would make more sense to treat the odors as at least potentially harmful and to be avoided. Certainly even a casual literature search readily finds studies citing potential health effects and complaints from exposure to at least certain if not a wide variety of those oxidized-plastic (such as PVC) odors and gases.
You might try a smell patch test to see if you can identify the worst odor source so that that material, e.g. carpeting, can be replaced. I've found that it can take a long time for such odors to dissipate, and in some cases they never completely dissipate until the odor-source material is replaced.
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