Rodents in Car Engines and Garages

Mice and rats get into car engines and garages for warmth and shelter, and they bring nesting material with them: leaves, insulation, paper and seed. A vehicle or mower that sits for days or weeks is the most likely target. Signs include nests under the hood or in the air filter box, droppings on the engine or in the cabin, a musty smell from the vents and chewed wires or hoses.

The fix is the same as for the house, applied to the garage: remove food, seal the gaps, trap along the walls and check vehicles regularly. If you find a nest, clean it like any rodent nest. Wet it with disinfectant first and wear gloves, following CDC guidance.

Why garages draw rodents

Garages are often the biggest opening in a house. The bottom seal on a garage door wears out, the corners where the door meets the frame leave gaps and doors left open for an afternoon let anything in. NC State Extension says mice get through gaps of a quarter inch, and young rats too.

Then there is the food: birdseed, grass seed, pet food, chicken feed, recycling and trash. Add stored boxes, rarely used vehicles and quiet corners, and a garage is ideal habitat.

Around Asheville, many homes have detached garages, carports, workshops and equipment sheds near the woods. Deer mice and white-footed mice are common in those buildings, and that calls for careful cleanup.

Signs of rodents in a vehicle

Nesting material under the hood, on top of the engine, in the air filter box or behind the battery.
Droppings on the engine, in the trunk or in the cabin.
A musty or urine smell when the heater or AC runs, which can mean a nest in the cabin air filter or vents.
Chewed wires, hoses or insulation under the hood.
Warning lights or strange behavior after the car sat for a while.
Stored nuts, seeds or pet food tucked into corners of the engine bay.

If you find chewed wiring, have a mechanic check the vehicle before you take it on a long trip.

Cleaning out a nest safely

Follow the CDC's steps for rodent nests and droppings:

1. Open the garage door and let the space air out for 30 minutes before cleaning. 2. Wear rubber or plastic gloves, and consider eye protection. 3. Spray the nest and droppings with disinfectant, like a fresh mix of one and a half cups of bleach per gallon of water, and let it soak for five minutes. Be careful around electrical parts, and use a commercial disinfectant if bleach is not suitable for the surface. 4. Remove the nest and droppings with paper towels and put them in a sealed plastic bag inside a second bag. 5. Disinfect the area again, wash gloved hands, take off the gloves and wash your hands.

Do not use a shop vac or leaf blower on droppings. If the nest is in the cabin air filter or ducts, have a shop replace the filter and clean the ducts.

Mice in the garage again?

Your call goes to an independent rodent control provider serving Asheville and Buncombe County. Describe what you are seeing and ask for the plan and the price in writing before any work starts.

(828) 503-0038Tap to call · Free to call

Keeping rodents out of the garage and the car

Replace a worn garage door bottom seal and close the corner gaps where the door meets the frame.
Seal pipe, wire and vent openings into the garage with copper mesh or 00 steel wool and caulk, or hardware cloth.
Keep the garage door closed when you are not using it.
Store birdseed, pet food, grass seed and feed in metal bins with tight lids.
Keep trash and recycling in closed bins, and do not leave food in vehicles.
Set snap traps along the garage walls, in enclosed boxes if pets or kids use the space.
Start and use vehicles regularly, and pop the hood every week or two on cars that sit.
For long-term storage, check the engine bay and air filter box before starting.

NC State Extension says repellents are not a reliable way to manage mice or rats, so do not count on scent packs or ultrasonic devices under the hood. See do rodent repellents work?

Equipment, mowers and farm vehicles

Lawn mowers, tractors, ATVs, boats and campers that sit for a season are common nest sites around Asheville, especially on rural lots in Candler, Fairview, Weaverville and Black Mountain. Before using stored equipment in spring, check air filters, engine compartments and seat cushions for nests and droppings. Campers and RVs need the same cleanup steps as a cabin. See deer mice in cabins and outbuildings.

If mice keep getting into the garage and then the house, see mouse control or rodent exclusion.

Frequently asked questions

Why do mice nest in car engines?

Engines stay warm after a trip, offer sheltered spots and are close to food stored in garages. Vehicles that sit for days are the most likely targets.

Will mothballs or peppermint keep mice out of my car?

NC State Extension says repellents are not reliable for managing mice or rats. Remove food, seal the garage, trap and check the car regularly.

Is a mouse nest in my engine dangerous?

Chewed wires can cause problems, and droppings can carry germs. Clean nests the CDC way and have a mechanic check any chewed wiring.

How do I stop mice getting into my garage?

Replace the door bottom seal, close the corner gaps, seal pipe and vent openings and keep seed and pet food in metal bins.

Does car insurance cover rodent damage?

It depends on your policy. Call your insurer and ask before repairs, and take photos of the damage and any nests.

Get a rodent technician on the phone

Free to call. You are connected with an independent provider serving Asheville and the rest of Buncombe County. Same-day appointments are often available.