Keeping mice out of a car in winter storage

A car that sits for the winter is, to a mouse, a dry shelter with insulation inside. They climb up through the wheels and nest in the air filter box, the cabin air intake or under the seats, and they can chew wiring and hoses while they’re there. You find out in spring, from the smell in the vents or a warning light. A little work in the fall avoids all of it.

Before you park it

• Clean the inside. Wrappers, crumbs, a forgotten bag of dog treats, and even paper napkins are food and nesting material. Vacuum the seats and floor and empty the door pockets.
• Store it inside if you can. Make the building hard for mice to get into first. Our garage guide covers finding and sealing the gaps.
• Block the openings. Some owners push steel wool into the exhaust tip and over the air intake opening. If you do, hang a bright tag on the steering wheel saying so, and take it all out before you start the engine.
• Raise the hood. Many owners leave it open so the engine bay is less dark and sheltered. It costs nothing to try, though nobody can promise it works.

Trap around it, not in it

Mice have to cross the floor to reach the car, and that’s the place to catch them.

• Set traps along the walls nearest the car, and near where it sits. Mice travel along edges, not across open floor.
• More than one mouse is normal in a garage over a winter, so a trap that resets itself keeps working between your checks. A bucket trap catches mouse after mouse until you empty it.
• Keep traps set all season, and check them often. Every day is best.
• A bucket with water in it is a drowning hazard for small children and pets. Put it where they can’t get to it.

What isn’t worth it

• Mothballs. They’re a pesticide, and their labels say to use them only in tightly closed containers. Scattered in a car or a garage, they’re against the label, and the smell soaks into the upholstery.
• Poison. A poisoned mouse doesn’t die on the spot. It can crawl into a vent or under the headliner first, where you can’t reach it, and pets and wildlife can find the bait or the mouse.
• Dryer sheets, peppermint oil, ultrasonic plug-ins. Popular, but the evidence that they keep mice away is thin. Don’t count on them by themselves.

In the spring, before you drive

• Remove anything you blocked the exhaust or intake with, and take down the tag.
• Open the air filter box and the cabin air filter housing, and look for nesting material.
• Look over the engine bay for chewed wires or hoses. If you find damage, have it checked before you drive.
• Run the fan on high with the windows down for a few minutes before you set off.

The same goes for RVs, boats, mowers and tractors

Anything that sits all winter with a sheltered space inside gets the same treatment: clean it out, block what you can, trap around it, and check it before you use it in spring.