Chlorine dioxide vs. mold

my 2004 vw jetta was stored for a couple of months and now has a moldy smell.

the smell isn’t coming from the ac vents. it seems more connected to the upholstery and carpets.

i’ve cleaned the car and shampooed everything twice. i’ve also had the car professionally cleaned. the smell returns after awhile.

looking around for a fix, i came across reference to a chlorine dioxide generator called “auto vaccine”.

has anyone used this? is it effective? or just snake oil…

i’m trying to avoid having to replace the entire interior if possible.

Here’s one set of ideas:
Have you called around to auto detailers in your area? Not for cleaning, but for odor removal? If it were me, I might use something like a Bissel carpet cleaner, but instead of shampoo, I’d use an odor eliminator, like Odoban. I haven’t tried that, haven’t had the problem. Key is making sure the car can dry thoroughly (warm, fans, etc).

Chlorine dioxide? They must have won the Nobel prize for chemistry because I doubt such a chemical exists.

Well it does exist, but it is an explosive and it set off by light.  I don't think I would use it on my car.

The referenced material might help, personally I would not want to play with the stuff when there are known proven materials. Call one of the companies that specialize in restoring homes after fires. They will have an industrial ozone machine if that is what is needed, they are also experienced with finding those problems and using whatever techniques are needed to correct the problem.

If you want to use chlorine dioxide, I’d suggest a mold remediation service rather than a DIY generator. They are used to working with the gas and will likely be able to do the work for less than the cash outlay and hassle of doing it yourself. It’s a good approach since it breaks down into a salt leaving no harmful residue. However, it’s no guarantee that the mold won’t return. This is another reason to consult a pro. They can test to find out EXACTLY what it is prior to performing any eradication procedure. Then, use the least costly and most effective treatement to get rid of it.

Chlorine dioxide (ClO2) is commonly used in municipal water treatment systems. It kills germs and removes odors. It is also used commercially in bleaching. ClO2 is a gas but never used as such, only in water solutions up to about 15% concentrations. At such levels it is reasonably safe and easy to handle.

I do not advise using for odor removal of upholstery. It will bleach the fabric, and do so unevenly. Chlorine dioxide is not intended for this purpose.

It is also used commercially in bleaching. ClO2 is a gas but never used as such, only in water solutions up to about 15% concentrations

It’s been used a fumigation gas for some time. Lots of references to such, here’s but one for your convenience-

Nu Calgon BioFresh


The Auto Vaccine uses NosGUARD by Avantec Technologies Inc. It is the real thing and will work as advertised eliminating mold, mildew and odors from your car.

Chlorine dioxide is dangerous at high concentrations, but the Auto Vaccine does not come close to those concentrations. On the other hand, if you happen to notice a greenish/yellow cloud forming inside your car, you probably want to open the door and let it air out for a minute or two before getting in.

Avantac Technologies and developed a method of using chlorine dioxide that is very easy to use. Just pop the pouch in some water, close the door, and walk away. After an hour or two, the job is done. Be advised that chlorine dioxide will kill mold and mildew, but it is not a detergent. If there is some mildew on the window sills, for example, you will still have to wipe the dead stuff off, but you can rest assured that it will be dead.

I have used a similar product to eliminate mold and mildew and odor from several cars, and it has worked wonderfully. I had to mix separate chemicals, then dilute and add to a spray bottle. The Auto Guard system looks much easier to use. Also, at the concentrations used, I have had no issues with bleaching rugs or seat fabric.

Chlorine dioxide also is effective in dealing with mold and mildew in basements, garages, and bathrooms. Avantec offers different strength packets, but I don’t know how available they are for purchase.


Interesting question. One day I got a call from one of my sales reps. She reported leaving her car window open at night and a male cat got in the car and marked it with urine. It had a terrible smell. I referred her to find a detail shop to get the upholtstery cleaned. She did, 3 attempts in 2 weeks and the smell was better but still pretty tough to take. I had to ride with her about 2 weeks later and I could hardly stand it. We were riding in the middle of winter with the windows wide open. About 6 months later the odor just miraculously disappeared.

Try everything you can, but if it doesn’t work keep airing the car out and eventually it will go away - maybe.

My parents had a problem with a moldy smell in their truck. Turns out there was a leak, but having the windows up all of the time caused mold to grow in places it could not be cleaned out of. For example, under the seats, under the carpet and padding, inside of all of the body panels and even in the seatbelt reels.

They and the dealer tried everything, including the chlorine dioxide, but the smell kept coming back. Once the leak was fixed (shouldn’t be an issue with your car, just keep the windows down a few inches if you store it again, presumably in a garage or someplace water won’t get in) the entire interior was replaced. New seats, carpet, panels, headliner, blower system, dashboard, EVERYTHING was replaced to keep the mold from coming back. Just a hot, humid summer day would have caused enough moisture to condense inside and get the mold growing again since the spores can last through just about anything!

I thought I’d post my results with this product.

I have an '04 Camry that is parked outside. Shortly after buying it. chipmonks or mice got into the ducting from the inlet air snorkel. They were able to slip past the cabin filter to gain access to the cabin. After I realized what had happened, I evicted them, cleaned out the ducting and interior as best possible and afixed a screen over the inlet to prevent them returning.

Warm, humid days were the worst for the residual smell. A distinct urine odor would permeate the interior on humid days and only get worse if it was hot outside. It was gradually dimishing with the emphasis on gradual.

I ordered one of these Auto Vaccine “kits” on Sunday night and it was delivered in the mail on Tuesday. Amazing. Anyway, I followed the instructions and ran the fan on recirc for about an hour during the 4 hour treatment time. You could smell the gas some distance from the car so I knew it was working. It smells like an offbeat chlorine odor that takes some time to dissipate. It’s been about three weeks since I did the treatment and it smells like a brand new car. There is no hint of the prior smell and we’ve had a number of days were it would have been quite noticeable. It still smells slightly of the chlorine dioxide but it rapidly diminished to the point it pleasantly refreshing. I wouldn’t hesitate to use it again if the need arises. IMO, they delivered on their promise and I’m very happy with the result. YMMV.

ClO2 is also the active ingredient in an orally taken solution (called MMS) used by infected people to fight malaria and other parasites as well as yeast infections. It has been used throughout some of the African nations as well as other places.

Auto vacainne could start your car on fire,i sold this product and had a car start on fire!
Would recommend odor rescue its new and i think much safer to use

I cannot see how that is possible unless you intentionally disregard all of the instructions and even then it’s a stretch.

Just to add one item, (maybe someone already noted it, but I did not see it) mold smells often come from leaves dust etc, forming in the area under the grill right in front of the windscreen. The drain for that area can get blocked so it just forms again faster than you can spray or kill what is there, if you don’t address the root cause.

Good luck

chlorine dioxide? I’m a chemist. no such thing.

Sorry, it exists but it’s an unstable radical. mostly used for pulp bleaching

Chlorine Dioxide is used in disinfection, sterilization and even water purification. It is very safe if EPA registered and produced by a credible chemical manufacturer. The Auto Vaccine despite all the competition slandering the product has NEVER caught fire and has no lawsuits pending or any lawsuits ever regarding this product