Dead Animal Smell in Car: How to Find the Source and Clean It Up

A dead animal smell in a car usually has a hidden source, and the first job is finding it without stirring up what the animal left behind. This guide covers where rodents and squirrels nest in a vehicle, how to check those spots, the cleanup steps the CDC and King County Public Health publish for dead rodents and nests, and what the EPA says about ozone generators sold for odor control.

Identifying The Source Of The Odor

King County Public Health says rodents, including squirrels, mice and rats, may build nests in cars, trucks, campers and other vehicles, and that this is more likely if the vehicle is not used often. Its King County Public Health page on cleaning rodent-infested vehicles lists where nesting materials turn up. The CDC adds that when you inspect, you are looking for dead rodents, nesting materials and rodent waste such as urine or droppings.

Area of the vehicle	What King County Public Health says
Engine compartment	Nesting materials can be in the engine compartment insulation. Common spots are between the battery and the vehicle frame and near the windshield wiper motors, plus underneath air intake ducting or inside the air filter.
Air intake and HVAC ducting	Rodents may build nests on top of accordion-style air filters or in hoses and ducting that lead directly to the passenger compartment. Nesting materials in the air intake can also cause odors inside the passenger compartment.
Passenger compartment	Nesting materials can be in the headliner, the glovebox, and in or under the seats.
Trunk	Nesting materials can be in the trunk, including the spare tire compartment.
Tool compartments and light enclosures	Tool compartments and the access areas and enclosures for taillights and headlights are also on the list.

The same page names the entry points: rust holes, wire chases, side vents, rocker panels and ducting.

Why Rat and Rodent Droppings Need Careful Cleanup (Hantavirus Risk)

King County Public Health says some rodents, such as deer mice, can carry hantavirus, and that their nesting materials, droppings and urine may contain it. It adds that people cleaning or riding in the car may come into contact with infected materials, and that infectious virus particles may blow onto passengers through the air vents.

The CDC says rodent diseases are mainly spread to people when they breathe in contaminated air, which is why it says not to vacuum or sweep rodent urine, droppings or nesting materials: doing so can put tiny droplets containing viruses into the air. If you already vacuumed, the CDC says to follow its cleanup guidance. It also notes that fleas are common on rodents and suggests insect repellent such as DEET or another EPA-registered repellent on clothing, shoes and hands while picking up dead rodents and cleaning nesting materials.

Protective equipment the CDC lists

For ordinary cleanup the CDC says to wear rubber or plastic gloves, and its vehicle instructions add a long-sleeved shirt. For heavy rodent infestations in homes or buildings it lists coveralls (disposable if possible), rubber boots or disposable shoe covers, rubber, latex or vinyl gloves, protective goggles and a respirator. It says the respirator should be a half mask air-purifying respirator with a HEPA filter or a powered air-purifying respirator with HEPA filters, with local and state fit-testing requirements followed. The CDC also says to consult a qualified mechanic or automotive professional for help with a vehicle.

Immediate Actions To Take

Both the CDC and King County Public Health start with airing the vehicle out. Per the CDC guide “How to Clean Up After Rodents”, open the hood, vehicle doors and trunk so the interior and engine compartment air out for 20 minutes, and do this in a well-ventilated space. King County gives the same 20 minutes and says to do it in open air.

1. Put on plastic gloves and a long-sleeved shirt, as both agencies say.
2. Before inspecting the engine compartment, remove the cables from the battery to avoid shock. King County says this is to reduce the likelihood of being shocked while cleaning out nesting material. Both agencies say to reconnect the battery only when the sprayed area is dry.
3. Inspect the interior and the places in the table above for dead rodents, nesting materials or waste. Check the air intakes and filters before starting a vehicle that has sat idle for an extended period.
4. Do not use a vacuum cleaner, a broom or a high-pressure sprayer on urine, droppings or contaminated surfaces until they have been disinfected. King County says the vacuum or broom could create potentially infectious aerosols and that power washing should not be used to soak or dislodge nests or droppings.

Diy Cleaning Methods

Removing a dead rodent or nest

The CDC guide “How to Clean Up After Rodents” gives these steps for a dead rodent or a nest. They are the same steps whether the animal turns up under a seat, in the trunk or in the engine bay.

1. Wear rubber or plastic gloves.
2. Spray the dead rodent, the nest and the surrounding area with a disinfectant and let it soak for 5 minutes, or for the time on the disinfectant label.
3. Place the dead rodent or nesting materials in a plastic bag together with any used traps.
4. Tie the ends of the bag in a knot, then place the full bag in a second plastic bag and knot that one too.
5. Throw the bag into a covered garbage can that is regularly emptied. The CDC says you can alternatively contact your state health department about other ways to dispose of dead rodents.
6. Wash gloved hands with soap and water or a disinfectant before removing the gloves, then wash hands with soap and warm water after removing them.

UC IPM, the University of California statewide pest management program, gives similar advice in its Rats Pest Notes: use disposable gloves, never touch rodents with bare hands, and dispose of them in a sealed plastic bag in the trash.

Choosing and using the disinfectant

The CDC says to use a general-purpose household disinfectant, confirming the word “disinfectant” is on the label, or a bleach solution. Its bleach recipe is 1.5 cups of household bleach in 1 gallon of water, which is 1 part bleach to 9 parts water, made fresh before use. King County gives the same 1 to 9 mix for vehicles and adds that you can follow the manufacturer’s instructions for dilution and disinfection time instead.

The EPA page “Selected EPA-Registered Disinfectants” says disinfectants are pesticides that can be harmful, so read the precautionary language before use, and that the Directions for Use section gives the contact time, which is the time the surface must stay visibly wet for the product to be effective.

Fabric, carpet and upholstery

The CDC says to follow its soft-surface steps after urine and droppings have been sanitized and removed: launder potentially contaminated clothing or bedding in hot water with detergent and machine dry on high or hang in the sun, and shampoo carpets and upholstered furniture with a commercial disinfectant, a commercial-grade steam cleaner or a shampoo.

Item	Step from the CDC guide
Dead rodent or nest	Spray with disinfectant, soak 5 minutes or per label, double-bag, put in a covered garbage can
Carpets and upholstery	Shampoo with a commercial disinfectant, a commercial-grade steam cleaner or a shampoo
Cloth items taken out of the car	Launder in hot water with detergent, machine dry on high or hang to dry in the sun

Professional Odor Removal Services

Some jobs are not for a driveway. The CDC says to contact a professional rodent exterminating service to remove rodents when there is evidence they have accessed heating and cooling ventilation systems, and notes that duct cleaning companies are familiar with the problems and risks of rodent infestation in ventilation systems. For vehicles, King County says that if the infestation is extensive, you may need to replace hoses, ductwork, filters, fans or other components, and qualified mechanics or automotive professionals should do the inspection and cleanup.

King County says to tell the mechanic about the potential for hantavirus. The CDC likewise says to consult a qualified mechanic or automotive professional for assistance with a vehicle.

Dealing With Lingering Smells

Once the dead animal, nest and waste are out, the EPA’s indoor air guidance explains why the order matters. Its EPA page “Ozone Generators that are Sold as Air Cleaners” lists three approaches to indoor air pollution in order of effectiveness: source control, ventilation, then air cleaning. It says source control is the most effective, that ventilation by outdoor air is also effective, and that air cleaning is not generally regarded as sufficient by itself but is sometimes used to supplement the other two. It also says gas-adsorbing material is sometimes used to remove gaseous contaminants when source control and ventilation are inadequate.

What the EPA says about ozone generators

Ozone generators are marketed for odor removal, so the EPA’s position is worth knowing before you buy or rent one. The agency says:

• No agency of the federal government has approved ozone generators for use in occupied spaces.
• Ozone is a toxic gas. When inhaled it can damage the lungs, and relatively low amounts can cause chest pain, coughing, shortness of breath and throat irritation.
• At concentrations that do not exceed public health standards, ozone has little potential to remove indoor air contaminants. It says some experiments suggest body odor is masked by the smell of ozone but not removed.
• High ozone concentrations are sometimes used in unoccupied spaces for odors, but conditions should be controlled so that no person or pet is exposed. Ozone can damage materials such as rubber, electrical wire coatings and fabrics.
• Even at high concentrations, ozone may have no effect on biological contaminants embedded in porous material.

The EPA also says lack of an ozone smell does not guarantee levels are safe, because the ability to smell it varies and deteriorates in its presence. Our guide on running an ozone generator in a car covers the vehicle side.

Preventive Measures

The CDC says snap traps and poison baits are effective in stopping rodent access into vehicles, that rodents can enter the passenger compartment through ducting, rusted areas and cable conduit, and that food of any kind left in the car can attract them. King County says regular exterior and interior inspections help prevent infestations.

Poison baits come with a warning that matters for this topic. UC IPM says dead rats can contain several lethal doses of anticoagulant toxicant, that secondary poisoning of pets and wildlife is possible if they eat rat carcasses, and that the best precaution is to keep pets away from rodenticide baits and dead or dying rodents.

Related guides: keeping mice away from cars, preventing rodents in your car, getting a rodent out of your car, mouse odor in a vehicle, musty smells, car odor eliminators and cabin air filter changes.

What This Guide Does Not Cover

This guide does not cover birds or larger animals such as deer, because the cleanup sources used here are written for rodents. It does not give repair prices or odor timelines; ask a shop for an estimate.

Keep reading

• Why Does My Car Battery Smell Like Rotten Eggs? Explained
• How To Remove Mold And Smell From A Car For Good
• How to Get Rid of Mold in a Car Interior (Plus the Smell)

Frequently Asked Questions

Why Does My Car Have A Dead Animal Smell?

King County Public Health says rodents, including squirrels, mice and rats, may nest in cars, trucks and campers, and that nesting materials in a vehicle’s air intake system can cause odors inside the passenger compartment. The agency names dead rodents, droppings and nesting materials as the evidence of rodent activity.

How Long Does It Take For Dead Mouse Smell To Go Away In A Car?

No CDC, King County or EPA page cited here gives a number of days. The EPA says source control, which means eliminating or controlling the pollution source, is the most effective approach to indoor air pollution, followed by ventilation with outdoor air.

Why Does It Smell Like Something Died In My Car Vents?

King County lists the ducting and air filtration components of a vehicle’s heating and air conditioning system among the places nesting materials are found. The CDC says to contact a professional when rodents have accessed heating and cooling ventilation ducts.

How Do I Get The Dead Animal Smell Out Of My Car AC?

King County says that if infestation is extensive, hoses, ductwork, filters, fans or other components may need replacing, and that qualified mechanics or automotive professionals should do the inspection and cleanup and be told about the potential for hantavirus.

Can I Use An Ozone Generator To Remove A Dead Animal Smell From My Car?

The EPA says no federal agency has approved ozone generators for use in occupied spaces and that ozone is a toxic gas that can damage the lungs. It says high concentrations in unoccupied spaces must be controlled so no person or pet is exposed.