Dog as pet smell source in car (C) Daniel Friedman How to Find & Remove Odors, Gases & Smells in Cars, Automobiles, Boats, Trucks, Campers

  • CAR SMELL & ODOR Diagnosis - CONTENTS: Car smell diagnosis & cure; smelly autos, cars, campers, trucks - Cause & cure of moldy car smell - is it a dead animal? a fish? List of common car smells and what causes them; Typical levels of VOCs and most common chemicals in "new car" plastic smells
  • POST a QUESTION or READ FAQs about diagnosing and cleaning up mold or mold smells in vehicles: cars, boats, RVs, campers, airplanes, trucks

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Car smell diagnosis: this article series explains how to find, diagnose, test, identify, and cure or remove a wide range of obnoxious or even toxic odors in cars, trucks, campers, boats, and similar vehicles.

Smells in a boat, car, camper, or truck may be due to a range of problems ranging from dangerous burning brakes or an actual engine fire, to leaks in the climate control system, to hard-to-cure mold contamination of carpeting, seating, headlines, and sound proofing.

This article explains the range of causes of odors in vehicles, what they might mean, and how best to get rid of the offensive, unhealthy, or unsafe smell.

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Boat, Car, Camper Odor Diagnosis & Cure Guide: How to Find, Test, & Remove Odors, Odor Detection, Smells, & Gases in Vehicles

Moldy car smell - how to find and get rid of car mold odor (C) Daniel Friedman

The photo at the top of this page shows how pet odors can become pervasive in a car, noticed more by occasional passengers than the car's owner.

But at left we are dealing with a car that stinks of mold, not dog odors nor cat pee. Details of this successful car deodorization process are included in this article.

Article Contents

Foul smells in cars tend to be particularly troublesome to drivers and passengers who find themselves enclosed in a comparatively small space where airborne particles, gases, smells, stinks, and odors may appear to be concentrated.

Lowering windows may provide temporary but certainly not all-season relief from car smells.

Car Burning or Gas Smell Safety Warnings: Vehicle Smells May Indicate Safety Hazards: Burning Brakes, Car Fires, Electrical Fires

Some vehicle odors need to be diagnosed virtually immediately if they might indicate a safety hazard. Some examples include:

Smoky burning car smells or odors - possibly traced to a locked emergency brake, a stuck, failing main braking system component, or even an engine fire: burning electrical components, an oil or gas leak in the engine compartment, or a similar condition can set a vehicle on fire.

Stop your car and investigate burning odors immediately or as soon as you can pull safely out of traffic.

But be prepared to quickly get everyone out of the car and to a safe location away from the vehicle if you see or smell smoke. As he drove down the Garden State Parkway, our brother-in-law smelled something like smoke coming from the foot-well or dashboard of his Corvette. When he slowed down to pull in to a toll booth, smoke began curling up from the car's dashboard.

David quickly realized that only the wind from highway speed had been keeping the car from bursting into flame. He leapt from the car, leaving it stalled right in the toll booth, and ran for a fire extinguisher. In moments the engine compartment was a roaring fire that in turn set the fiberglas Corvette body on fire as well.

Prompt aid from the fire department put out the burning car and saved the toll booth from more than Corvette-smoke damage. David was, however, not very popular with the toll booth attendants. The car was a total loss.

More recently, stopping to aid a motorist in the off-roads of central Mexico, we noticed the characteristic burning plastic odor of an electrical fire coming from the engine compartment of a pickup truck. Luckily, by quickly turning off the ignition switch (we might have needed to also disconnect the battery but not in this case), the electrical wiring stopped overheating and we were able to avoid a more serious fire.

Burning Smells in Cars: burnt oil, burnt plastic, nasty dead fish, maple syrup

Other burning smells from cars have been reported and discussed on Car Talk and include sources such as

Car Odors - Animals that Cause Car Smells, Dead or Alive

Some possible sources of a "dead animal" smell in your boat, car, camper, or truck are worth checking out:

Animal urine, vomit, feces from pets or from animals that you should never have let in your car or boat in the first place, like Laura's groundhog that we discuss over at GOPHER HOLE DAMAGE.

Mice and rats like to nest in vehicles, both in the vehicle interior where there is lots of nice nesting material, and in the engine compartment where there are cozy, initially warm spots such as inside the air cleaner.

If you are having trouble starting the engine of a vehicle that has been stored over the winter, in fact maybe even before trying to start such a vehicle, check for a mouse nest in the air cleaner. It's a lot easier to clean out this mess before you try cranking the engine - a step that can actually suck nest material into the engine itself, causing worse problems.

Skunk smells on and in cars: lots of drivers know what happens if you run over a skunk, even a dead one. The smell seems to stick to tires and to the car under-side. It goes away with washing and time. But sometimes it's worth checking further to be sure your vehicle is not a coffin.

In college, our friend Sam was the first kid to own a new car, a beautiful Chevrolet Impala that the rest of us envied. Some of the fellows were more resentful than the rest of us, after noticing that Sam was more of a car utilitarian than a car enthusiast (he had never opened the hood nor trunk of his new car even to look inside). This lack of red-blooded American car-enthusiasm got their goat. Or skunk.

In what started as a bad practical joke, two fellows (not including the author) found a dead skunk - nearby road kill, and managed to place it (thoughtfully wrapped in newspaper) in the trunk of Sam's new Impala.

The skunk stunk, worse day by day. Finally, even Sam noticed the smell and came to the author asking "Dan, can you help me figure out why my car smells funny?" It didn't take long. We could smell the skunky Impala from 100 feet away. After a quick look under the front end for skunk parts, we noticed the smell was worse at the car's tail end - sort of like a skunk itself. We opened the trunk and quickly stepped back in disgust.

Removing the dead skunk from the trunk was not enough as now the whole car smelled horrible. Replacing the carpeting and mats took care of most of the skunky car trouble, and time did the rest. It was months, however, before anyone wanted a ride with Sam.

If you are struggling with a horrible skunk smell in your vehicle, and it's actually due to a skunk, check with a veterinarian who may have products and special advice for cleaning out skunk odors.

Squirrels also like to make a winter home in vehicles. Our friend Sam S. stored his Porsche boxer in our un-heated garage for months beginning in the fall. Other than driving the Porsche into the garage and turning off the engine, no other preventative measures were taken.

When Sammy returned to pick up his car we just handed him the key to the garage. A few minutes later he came back into our lab, scowling and angry. "It wasn't very funny what you did," he began. He went on to describe what he thought was our practical joke: filling the car's interior with leaves.

Dog as pet smell source in car (C) Daniel Friedman

We were not guilty. A closer examination showed along with leaves, lots of acorns, and worse, squirrel pee and poop throughout. The car was salvageable, but only after a lot of cleaning.

Pets in automobiles, especially in family's who may bring along several dogs on long rides, can make a car smell doggy even if no accidents (pet urine) ever occur in the vehicle.

Our photo (left) shows Rudy who was a frequent traveler in our daughter's car. Although Rudy never had an accident in the car, and though he was well cared for, Rudy's frequent travel left the car hairy and doggy, noticeable to passengers if not to Rudy's family.

In our experience the pet odor is more noticeable to visitors and occasional passengers than to members of a family who live with the pets.

Urine smells in cars: a urine smell associated with turning on the heater may be caused by a leaking heater core. But also check the heating and cooling system for mouse infestation of the ducts or heater.

Small animals may enter the vehicle's duct system or air box where they build a pee-smelling nest and where they might even continue to reside - until you start using the car again.

Because cleaning these components is time consuming, difficult, and costly, it may be less expensive to simply remove and replace these components unless on your particular vehicle they can be removed and thoroughly cleaned and disinfected with reasonable effort.

Urine smells can of course be caused by a bigger animal (including a human) peeing in the car. Ex wife No. 1 hated our cat, who returned the sentiment. While transporting the cat to the vet, everyone was nervous, including cat, who peed copiously on Harriet as well as on the seat and carpeting of the passenger side of our 1969 Karmann Ghia convertible. Forever after, no matter how much we cleaned the carpets, if we left the car parked in the sun with the top up, it was impossible to tolerate the cat pee inside the vehicle.

Spraying a deodorant into the vehicle's climate control system ducts will certainly not be effective if there is a nest or a dead animal in the system. If the recirculating control is set to shut off outside air and the smell is reduced or stops, that probably indicates that the animal or nest is in the engine compartment rather than in the portions of the climate control ducting in the passenger compartment.

Because cleaning a car's A/C system ducts and other components is time consuming, difficult, and costly, it may be less expensive to simply remove and replace these components unless on your particular vehicle they can be removed and thoroughly cleaned and disinfected with reasonable effort.

For details about animal smells in both buildings and cars, see our diagnostic article ANIMAL or URINE ODOR SOURCE DETECTION.

Rotten odors that smell like a dead animal, or garbage, may also be traced to food or drinks (including milk) spilled in the vehicle, especially if its passengers include small children.

Car Odors - Antifreeze Smell

Probably a leaky heater core - have it checked promptly. See Car Odors - Climate Control System, below.

Car Odors - Body Odor or "BO"

A "BO" smell in a car might be traced to occupants who needed a wash, or to mold growth in the A/C system. Some molds are known to produce a "dirty socks" smell. Ask your mechanic to check the A/C evaporator system and its drain port for blockage. -- Car Talk

A similar complaint of "stinky feet" smell coming from the car's A/C system might have had mold as its origin.

Car Odors - Cigars and Cigarettes

These smells are difficult to get rid-of without removing and replacing carpeting, seat covers, headliners, other soft goods or fabrics.

Removing these, cleaning the vehicle, and installing new materials may be effective. Before trying an ozone generator (that might help if it's not over done) see our warnings at our more broad discussion of use of OZONE MOLD / ODOR TREATMENT WARNINGS.

Car Odors - Climate Control System, Heating & Air Conditioning Causing Foul Car Smells

A/C evaporator leaks: The New York Times reported ("Shaky Seats, Leaky Fluids", 01/24/10) that "... some Toyota models may exhibit intermittent foul odors from the climate control system." The Times continued to note that Toyota has issued technical service bulletins for the 2006-2009 Toyota Rav4, the 2007-2009 Toyota FJ Cruiser, and the 2009-10 Toyota FJ Cruiser, as well as the 2009-10 Toyota Corolla.

The repair to remove the foul odor from these models involves replacement of the air-conditioner evaporator. The Times article as well as your Toyota dealer can provide the technical service bulletin numbers and details for specific models.

Coolant leaks into the duct work of a car's climate control system can be a source of a sickly sweet odor or other smells. The climate control system might, under some circumstances, also conduct exhaust smells, burning oil smells, fuel smells,or other odors from the engine compartment into the passenger compartment.

A clogged A/C system evaporator drain can cause condensate to accumulate in the climate control system, leading to both mold and even potential bacterial hazards. See the general discussion on Legionella BACTERIA & HVAC Equipment where we describe this hazard in building HVAC systems.

Spraying a deodorant into the vehicle's climate control system ducts will certainly not be effective if there is a nest or a dead animal in the system. If the recirculating control is set to shut off outside air and the smell is reduced or stops, that probably indicates that the animal or nest is in the engine compartment rather than in the portions of the climate control ducting in the passenger compartment.

Because cleaning a car's A/C system ducts and other components is time consuming, difficult, and costly, it may be less expensive to simply remove and replace these components unless on your particular vehicle they can be removed and thoroughly cleaned and disinfected with reasonable effort.

More about how odors move from one location to another through climate control or HVAC duct work in buildings (a similar but bigger problem than duct work in a car) is at DUCT & AIR HANDLER ODORS.

Car Odors - Exhaust Gas Smells Getting into Vehicles

Exhaust odors are a sign of trouble that may also be very dangerous: if you smell car exhaust while inside of your vehicle there may be a dangerous exhaust gas leak into the passenger compartment. Exhaust can enter the passenger compartment from the engine compartment, through the floor under the car, or even from an open car window, especially a back window or open hatch. CO hazards are discussed separately at Carbon Monoxide Gas Toxicity

Car exhaust is particularly dangerous for passengers riding in the enclosed or capped back of a pickup truck whose rear hatch has been left open, as air currents can draw exhaust into the vehicle even when there is no actual damage to the exhaust pipes or muffler.

Gasoline engine exhaust fumes are likely to contain carbon monoxide, a dangerous gas that causes first drowsiness (drive right into an accident?) and ultimately unconsciousness and death.

Have your vehicle and its exhaust system inspected by your mechanic if you smell engine exhaust in your vehicle. In driving your smelly car to the mechanic you might want to keep the front windows open as well.

More about the dangers of carbon monoxide and how we test for and correct CO gas leaks is found in these toxic gas articles - a sampling of a larger set of CO articles found at

Car Odors - Gasoline

You will not normally smell gasoline inside of a modern car unless you stepped in gasoline and tracked some into the vehicle, say at a gas station. However some plastic odors are confused for gasoline or other chemicals.

Gasoline smells in some cars (Subarus) have also been reported and traced to rubber hoses connecting the fuel rails to the fuel injectors. Leaks may be at the hose clamps, not in the hoses themselves. The symptom was a gas odor that appears mostly when the engine is cold and first started.

Gasoline smells are often traced to the vehicle's fuel system, piping, filters where an adjustment problem, mixture problem, or similar malfunctions; gasoline odors may be carried into the passenger compartment through openings in the fire wall or by an air intake leak into the vehicle's climate control system.

Car Odors - Mold: Boat, Camper, Car, or Truck Mold Contamination Can Cause Moldy Smells and May be a Health Risk

Car mold smell traced to carpeting and insulation (C) Daniel Friedman

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 buildings, also applies to cars) for details.

Here is our step by step moldy car cleanup guide

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.

  1. Identify the smell in the vehicle: is it mold or something else?
  2. Confirm that the moldy or "mildew" smell comes from inside the vehicle, ruling out having simply parked in a stinky area. Confirm that it's a moldy smell identify the smell in the vehicle to be sure it's "moldy" and not something else such as the other vehicle odors discussed throughout our vehicle-odor diagnosis article: BOAT & CAR SMELLS & ODORS
  3. Rule Out Indirect Odor or Smell Sources: Track the Stink to the Source, by ruling out odors that seem to be coming from a vehicle but actually come from an indirect source such as a boat cover, parking in a smelly area, etc.
  4. Find where in the vehicle the smell is strongest. Use the subjective test of a smell-test person, or if necessary, use our SMELL PATCH TEST to FIND ODOR SOURCE to confirm that the odor source is a specific item such as car carpeting, sound insulation, seat, or headliner.
  5. Look for and trace the source of water leaks into the vehicle. Mold needs water to grow, and food to eat - carpeting, plastic surfaces, cloth head liners, sound insulation, even paint will do. Mold does not grow on clean metal surfaces in a car.
  6. Remove moldy, smelly materials such as moldy carpeting or seats, clean the remaining car interior, and repeat the steps above. The moldy smell should be significantly less. It probably won't be completely gone, because the mold odor-source - the MVOCs that you were actually smelling, is a gas that also permeates other porous vehicle materials.
  7. Use "odor-killing" deodorants or ozone to get rid of moldy car smell? 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: Expert use of ozone might help reduce odors in a car, camper, van, or RV. But be very careful if you're going to permit someone to ozone-treat your vehicle. If the ozone treatment is over-done, the ozone can oxidize other car materials, causing a more horrible odor than ever. More about overdosing a car with ozone is at Ozone to Get Rid of Odors in a Car.
  8. Let the cleaned vehicle "cook" in sunlight on warm, dry days, with the car windows open.
  9. If the boat, car, camper, truck, or other vehicle still smells as bad 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.

Complete step by step details of how to find and remove moldy, musty, or "mildew" smells in cars and other vehicles can be found at CAR SMELL - Mold DEODORIZING.

Car Odors - Plastic Odors or "new car smell" - may be toxic?

Lots of new cars give off a "new car" smell that is a mix of volatile organic compounds out-gassing from new plastics and vinyls used in the car's interior. Usually this smell diminishes over the first few months of the car's life once it is in active use. However the outgassing from these materials can be substantial and is a respiratory irritant to some people.

Usually these new car "plastic" odors or "vinyl smells" are from VOC's from adhesives and vehicle interior components (vinyl and plastic headliners, dashboards, floor mats, carpets, etc) containing phtalates, an ingredient in vinyls and plastics used in cars, possibly also there may be VOCs and odors from paints and lubricants as well as in flame retardants used in some vehicles. .

According to a 2000 study by chemical engineers Grabbs et al, - these new car smells usually dissipate fairly quickly, 90% in 21 days, down to trace in in perhaps 60 days, especially in warm weather with windows open. The authors studied four new vehicles and found that three of them had total VOC concentrations (TVOC) 300 to 600 ug/M3 on the first day of testing. While over sixty chemicals were identified in the interior of the test vehicles, gases present at highest levels included toluene, ethylbenzene, xylene, and undecane. The study abstract did not mention vinyl chloride, nor "organotoxins" cited by other sources as a possible new car odor (and PVC vinyl shower curtain odor).

Watch out: We have received and also read of complaints of burning eyes, headache, and fatigue that some vehicle occupants ascribe to these chemicals. And indeed, as with mold exposure discussed above, particularly enclosing a sensitive individual (such as an asthmatic person) in a small space such as a new vehicle interior (windows shut, hot weather) where these gases are present could be a more immediate respiratory danger than the long-term exposure risks to carcinogenic chemicals that are unlikely to remain at high levels as the vehicle ages.

Also see Nitrogen Oxides Gas for a discussion of a possible problem with oxidized plastics that might occur if someone overdoses your car interior with an ozone generator while trying to get rid of an odor. Also see OZONE HAZARDS.

Standards for exposure to "new car" VOCs and chemicals?

To compare a government exposure standard to an actual measurement of gases or chemicals present in a new car, one will need to compare the exposure levels found, both instantaneous and time-weighted average exposure, to existing exposure standards for those chemicals, standards which may not have been written for vehicles, nor reflective of the variables - windows open or shut, temperature, duration, etc.

Watch out: But also watch what you spend on this topic: some of the car air purifier products sold to "remove" these gases may be both ineffective and unnecessary. It might be both effective and less costly to try opening the vehicle windows during the initial outgassing period for a new vehicle with smelly plastics or glues.

See Plastic odors for details about typical sources and cures for plastic odors and for the relationship between plastic and vinyl outgassing and heat or sunlight.

Car Odors - Sweet Smells

Antifreeze leaks in a vehicle may produce a sweet smell that enters the passenger compartment, especially if a heater core is leaking antifreeze into the duct system. This smell has been described as sickly sweet, or even cupcakes.


Continue reading at CAR SMELL - Mold DEODORIZING or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

For illustrations of a vehicle that was mold-contaminated beyond salvage and a study to identify the types of mold found in vehicles see CAR MOLD CONTAMINATION.

Or see these

Boat, Car, RV, Truck or Aircraft Odor Articles

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