"You can buy the most reliable car on Earth and still find convoluted electrical gremlins, fluid leaks, and even outright failure when rodents take up residence and begin chewing on wiring, hoses, plastic, and other critical car parts. But we’ve found a deterrent for these four-legged terrorists.

Rodent-inflicted damage is an age-old problem that some observers say is increasing as automakers use more plant-based biodegradable materials to reduce waste. It turns out that rodents sharpening their teeth and feasting on cars is more prevalent than you might think. We uncovered various technical service bulletins from Ford, GM, Honda, Toyota, and Subaru instructing their technicians how to remedy chewed wiring harnesses. So many people have been looking for solutions that the topic was trending on Reddit recently.

Readers posted several solutions, from covering the wires with a metal mesh to painting them with hot sauce. Some Consumer Reports staffers also have stories of small furry creatures chewing through power steering lines, filling engine intakes with acorns, and plugging up air-conditioning ducts with their nests.
What you can do

We found a clever solution in a TSB from Honda: rodent-deterrent tape, essentially an electrical tape treated with super-spicy capsaicin, which Honda describes as “the stuff that puts the fire in a bowl of five-alarm chili.” The tape (part number 4019-2317) is available through dealers for about $36 for a 20-meter roll, about 22 yards. You'll also find it online.

We bought a roll of rodent-deterrent tape to check out. Beyond the cute rodent graphics and gray color, it deceptively seems like regular electrical tape to us humans. There is no tear-inducing odor, but it does carry a label that warns against prolonged exposure to skin. Despite dares and double dares, we did not taste it and will trust that it is potent enough to deter even the most ravenous varmint.

Other suggestions for dealing with rodents under your hood include installing a metal mesh around wiring harnesses and rubber hoses and across any openings where rodents could crawl into your ventilation or intake systems. Or you could put mouse poison mixed with peanut butter around your garage for a more severe solution."