When a mouse, rat, squirrel, or other rodent decides to make its home in a car, truck, or RV, the resulting mess and damage can cost thousands of dollars to fix and can even expose the owner to rodent-borne diseases and parasites in the interim.
Rodents have always been attracted to the protection offered by junk cars or old semi-retired trucks and parked out back. Rodents might tear up air filters for nest material, nibble on hoses, or fill the engine compartment with leaves, nuts, droppings, copper, and babies. Nuts and other food that is cached under the hood by packrats or others can be a safety hazard and secondary pest problem. But in recent years, its new model cars with their many more wires and sensors that are the attraction. Any auto repair shop will tell you that they have no end of vehicles with gnawed wiring: ignition wiring, spark plug wires, brake sensor wires, etc. They often required an entirely new wiring harness to the tune of $2,000 plus.
Why is this such a problem? In the early 2000’s, car manufacturers began using bioplastics to make their manufacturing process more" green" or environmentally friendly. The problem arose because the biodegradable bioplastics used for wiring insulation and some other parts are soy-based. Soy, of course, is a plant-based material. We eat it; rodents eat it. Maybe not such a great idea.
Vehicles at most significant risk are those that are parked outside overnight. Those that are infrequently used or are half-buried in weeds or even more attractive to rodents. In winter, especially, rodents appreciate the dry, protected shelter under the hood. If they're lucky, there's even some residual warmth left from the engine. If they're fortunate, they can get into the cab area with fast food bags, clutter, and miscellaneous nest material.
Insurance and warranties often won't cover natural rodent damage. Experts say it may be covered if the owner purchased comprehensive coverage that includes non-collision damages. Plenty of disgruntled vehicle owners have put out thousands of dollars to repair annoying rodent damage to the wiring system. One website writer has had both his 2015 Honda Civic and his 2012 Hyundai in for repairs to the tune of $2,400 and $9,300, respectively. Class action lawsuits against several manufacturers have been filed.
If the vehicle is garaged, your job of trapping the offending rodents is much easier. If the car is parked outside or squirrels are the culprits, control is difficult. The emphasis is on prevention and making the vehicle less available and less desirable to rodents. For starters, relocate the car or remove nearby garbage containers, bird feeders, tall weeds, brush, etc., that offer food and shelter where the vehicle is parked.
Things You Can Do
Vehicle owners with expensive or repeat wiring or other rodent damage have come up with a range of fixes from spraying peppermint oil into the engine compartment, to placing a rat trap in front of and behind each front tire (the rodent access points to the engine compartment), to shining lights on the wheels or engine compartment at night.
- The obvious first step is to garage the vehicle. Garage doors can often be sealed to keep rodents out. Opening the hood at night will eliminate the allure of that warm, dark nest site.
- Ensure the garage does not attract or housing mice by removing or sealing pet food, birdseed, grass seed, produced, and garbage. Rodent proof the garage and garage door.
- Make sure the vehicle interior is not attracting rodents. Clean out clutter and food debris. Check under the hood often for damage or nest material.

- Special irritating “chili pepper”, wiring tape is available as is repellent or scented spray. As with all pest repellents, expect limited success.
Things Not to Do
Be careful about what kind of odor or taste repellents (red pepper, mothballs) are sprayed or placed in the engine compartment. Odors from the compartment may be drawn into the cab when the heat or AC is on. Do not place dryer sheets or anything that can catch fire under the hood and remove nest material for the same reason.
You must take precautions against stirring up airborne disease organisms such as hantavirus when cleaning out rodent nest material. Spray the nests and droppings with disinfectant and let sit briefly. Wear gloves and a respirator and bag and seal the nest material. Call us at 561-791-2400 for help protecting your car from rodents.