Why Mice Like Car Engines

Mice can cause a lot of damage if they get into your car's engine. They like to chew on wires and insulation, which can lead to electrical shorts and fires. Mice also leave droppings, urine, and nesting materials behind. Unfortunately, car engines provide everything mice are looking for - warmth, shelter, and food sources. There are a few key reasons mice are attracted to car engines:

Prevention Tips

The best way to keep mice out of your engine is through prevention and making your car less appealing to them:

Park Vehicles in Garages

If possible, park your vehicle in a garage. This eliminates access for mice since they have to remain outdoors. Indoor parking is the #1 way to prevent mouse infestations under the hood.

Use Repellents

Apply commercial mouse repellents made with natural ingredients around the engine compartment. Strong smells of peppermint, garlic, cloves, or chili pepper irritate their respiratory systems and deter mice. Reapply repellents frequently, such as once per month.

Eliminate Food Sources

Be diligent about cleaning up food spills in the cabin and trunk of your vehicle. Vacuum regularly to remove crumbs and debris mice might eat. Avoid keeping snacks in your car. Removing these food sources helps make your car less attractive.

Seal Entry Points

Seal any visible gaps with silicone caulk or metal mesh. Pay special attention around the firewall, fender wells, and underside of the vehicle. Blocking entry prevents mice from getting in to build nests.

Change Parking Habits

Avoid parking near dumpsters, tall grass or piles of debris mice might hide in. Keep your parking area clear of clutter and food trash that could attract them.

Natural Mouse Deterrents

If mice are already present, there are some DIY methods you can try using natural ingredients found at home:

Peppermint Oil

Mice strongly dislike the smell of peppermint. Soak cotton balls in peppermint oil and stash them throughout the engine compartment. Reapply the peppermint oil every few days to maintain the scent. Be sure to test for colorfastness before applying peppermint oil on any fabric surfaces.


Mothballs containing naphthalene or paradichlorobenzene can repel mice due to their strong odor. Scatter mothballs under the hood and replace them monthly. Do not inhale mothball fumes and make sure the engine is cool before use. Do not use mothballs on newer cars as they can damage sensors and rubber components.


The pungent smell of ammonia irritates rodents. Dip rags in ammonia and place them in areas mice frequent under the hood. You can also soak cotton balls and place them in small mesh bags. Be very cautious when working with ammonia as it can be toxic if used improperly. Never mix ammonia with bleach.

Cayenne Pepper

Sprinkle an even coating of cayenne pepper in the engine compartment and surrounding areas. The spicy capsaicin in the pepper aggravates mouse respiratory systems. Be careful not to get cayenne pepper near your eyes or face. Reapply after rain or every 2-3 weeks.

Physical Deterrents

Some simple physical barriers can also keep mice away from your car's engine:

Steel Wool

Steel wool is uncomfortable for mice to crawl over and acts as an abrasive barrier. Stuff pieces of steel wool into any visible openings. Avoid using steel wool near moving parts or anything electrical.

Copper Mesh

Copper mesh can be shaped into balls or strips and placed in the engine compartment. Mice receive a natural shock if they chew or touch copper. The metal is also difficult to gnaw through. Use hvac tape to hold copper mesh in place.

Mesh Screens

Cover air intakes or other vents with stainless steel mesh screens. Secure the mesh with hose clamps or zip ties. The fine mesh prevents mice from squeezing through while still allowing airflow.

Motion-activated Devices

Place battery-operated ultrasonic repellers or motion-activated air sprayers under the hood. They will turn on when mice are detected and startle them with lights, sounds or blasts of compressed air. These devices need occasional battery replacements.

Inspection & Cleaning

To deal with an existing mouse problem, you'll need to fully inspect for damage and sanitize the engine:

Staying vigilant is key to keeping mice out of your car's engine. Combining preventive steps with natural deterrents can help you safely and humanely protect your vehicle. Act quickly if you do spot signs of an infestation to prevent costly damage. With some proactive effort, you can enjoy mouse-free driving!