By on May 17, 2018

Shortly after the dawn of new millennium, automakers started implementing bio-plastics made from corn starch, genetically engineered bacteria, or vegetable fats and oils. The rationale for this was that sustainably sourced materials were better for the environment and lowered dependency on petrochemicals. Unsurprisingly, bio-plastics gained in popularity at roughly the same time as ethanol.

Since at least 2010, soy-based bio-plastics have been a popular alternative for wiring insulation in automobiles. But there’s a problem — rodents love how it tastes. This has allegedly resulted in a surprisingly high number of owners reporting that rats chewed through the wiring inside their automobile.

While the problem isn’t entirely new, the frequency of the incidents appears to have been spurred by automakers using more palatable materials. In fact, the issue has grown so bad in recent years, numerous lawsuits have cropped up demanding manufacturers pay for damages. Honda was named in a suit from two years ago involving 2012 to 2015 model year vehicles, and Toyota was hit with one for cars produced between 2012 to 2016. 

Bio-plastics were in widespread use at this point. Both Kia and Hyundai were named in subsequent rodent-related lawsuits, and practically every major manufacturer uses plant-based plastics on at least a few models built within the last decade. It sounds benign but, considering that rats eating your car typically isn’t covered under a vehicle’s warranty, owners have to shell out hundreds if their insurer isn’t interested.

According to the Detroit Free Press, the growing rat problem isn’t the result of paranoia, either. John Pappas, owner of Main & Hudson Service in Royal Oak, Michigan, claims he sees at least one vehicle every month with gnawed-on wires. “They’re going environmental on the wires,” he said. “There’s good and bad in everything. It is a common issue.”

Jim Stevens, a sales representative at Suburban Ford of Ferndale, stated finding rats chewing through wires “is a pretty common thing around here,” with around two or three vehicles coming in a month.

Brian Kabateck, a Los Angeles attorney is involved in a class-action lawsuit against Toyota Motor Sales, filed on behalf of an Indiana resident who watched his 2012 Toyota Tundra become a meal for rodents three times. Total damage was estimated at roughly $1,500, which Kabateck said Toyota won’t cover.

“Our contention, why soy is certainly — it’s laudable — they’re trying to be more green, at the same time, it’s becoming a potential food product for rats,” the attorney said, adding he’s not looking to make everyone rich. The suit is simply seeking reimbursement for damages and a new policy that would cover rat-damage under Toyota’s warrantee.

However, we don’t need to take the word of lawyers or service center employees. Owners are are willing to express their concerns on practically every online automotive forum. A cursory search for the term “rat” in numerous brand forums returned dozens of first-hand accounts from affected owners. Vehicles range from a Nissan Versa to a Jaguar XKR, but the vast majority share one common trait — they were built after 2005. Maybe it’s not telling, as fewer owners are worried about older cars. Still, there are decidedly fewer mentions on older threads.

Toyota claims rodent damage to vehicle wiring occurs across the industry, and the issue is not brand- or model-specific (which is true). It also noted that it was not familiar with any scientific evidence that rodents are attracted to automotive wiring due to alleged soy-based content.

Neither are we, but that isn’t stopping the public’s growing worry. Entire websites are devoted exclusively to tips on how to keep rats from eating car wiring. In the Free Press article, Janice Perzigian witnessed rodents do $600 worth of damage to her 2017 Ford Mustang. As a result, she takes time out of every day to surround the car with Pine-Sol, stuff the interior with dryer sheets, and spray down the tires with essential oils.

Forum solutions are frequently just as elaborate, often including plots to kill the varmints before they can get comfortable inside the engine bay. Our favorite reoccurring recommendation involves coating every single centimeter of wiring with hot sauce on a weekly basis.


[Image: Holger Kirk/Shutterstock]

Get the latest TTAC e-Newsletter!

41 Comments on “Rodents May Have Flavor Fetish For the Wiring Insulation in Newer Vehicles...”

  • avatar

    Picture is a gerbil. Just sayin’.

  • avatar

    I can’t keep mice out of my 2016 Rav4. I have caught about a dozen since last Fall when I discovered a mummified mouse in the cabin air filter. So far no wires have been chewed that I am aware of, but I keep thinking it is a matter of time.

    • 0 avatar

      If you drive daily, you will be fine. If you leave it for few days, you will regret

      • 0 avatar

        not true.
        i driver my mks every day.
        and, just this week, i lost my power steering and my dash lit like a christmas tree with showing abs, traction, awd, etc…all out.

        after a lot of work…it turns out a rodent had eaten my harness and hopefully the computer parts are ok.

        $2,200 in repairing so far.

        internet going crazy talking about these food-based firewall and wirings causing rodents to feast like kings and keep warm.

  • avatar

    A couple weeks ago at work, we got a couple raccoons on the lot overnight – someone discovered the next morning that they’d absolutely shredded the underhood insulation (and possibly some wiring) of two cars (out of hundreds), both Volvos. Something to keep in mind, I guess, if you live in a Trash Panda-infested area.

  • avatar

    Brilliant move industry! Especially after giant wheels, elimination of visibility and bumpers, awful styling, limited passenger/interior room, poor HVAC control design, weak powered drivetrains, weird auto transmissions, elimination of manual transmissions, and high, high prices.

  • avatar

    Planned obsolescence, green commie edition.

  • avatar

    I suppose something like heavy-guage vinyl flex conduit being used to shield the main run of wiring in underhood and exposed areas would be such an environmental travesty.

    Plastic junction boxes to branch the main run and those darned Molex connectors to make final runs replaceable would be so detrimental.

  • avatar

    Ray Charles saw this coming. Trendy ideas without any concern for the long-term effects of such decisions. Sound familiar?

  • avatar

    I had an ’02 Escape that I had to park on the street. Squirrels did $350 in damage under the hood.

  • avatar

    How hard can it be to add something to the soy plastic that rodents find repugnant?

    • 0 avatar

      That was my thought too. Similar to how something that smelled and tasted bad was added to coolant/antifreeze to dissuade dogs and cats from drinking this fluid if it leaked out of a car, which is poisonous.

      I’ve been lucky enough not to have my car invaded by rats, squirrels, or raccoons (though the latter two are common where I park). I do, however, get an ant infestation every summer.

  • avatar

    I had conversation with Mazda dealer earlier this year…. I found some shredded insulation on the top of the engine. I lifted the plastic engine cover and here we go – definitely something was chewing it. Not the cover but insulation under it. So, I called a dealer asking if there is recall/solution to this? they told me that rodents attack not only insulation but new wiring. And he told me, if my car is damaged – call insurance. I think, I will call a lawyer if it comes to that.

  • avatar

    Rats are driven to gnaw because their teeth grow constantly and they will die if the teeth get too long. So they’ll gnaw anything, including cinderblock in one place I used to live.

    In that same place, a couple of them got under the hood of my G8 GXP and severed a couple of wires. $300 to fix, most of which was labor to find and reach the wires in question. Pretty sure that insulation wasn’t soy based, and it didn’t matter.

  • avatar
    87 Morgan

    I had heard recently of an increase in the number of cars heading to the service department with rodent damage. Now I understand.

    I really don’t see how successful a lawsuit with the OEM’s is going to be. Rodent damage is not a new phenomenon for cars that are left to sit for any length of time. The frequency seems to be increasing, but I would think they can make the case that the owner of the car needs to take greater care to not park in a rodent zone or something like that.

    I am allergic to cats, but if I had this problem I would get some cats to live in the garage and they would most likely solve the problem.

  • avatar

    Spent $800 fixing my wiring harness last month for this very issue.

  • avatar

    I live in a condo in the sticks. I regularly see deer, wild turkeys, etc., I feed hummingbirds (only because I like to see them fly), but I digress.

    A 2014 Volvo had its alarm going off every 15 minutes, I finally turned into grumpy old man mode and notified the HOA.

    Yup, I busted them and the car was ultimately towed. Hate it for the owner, but I’ll be damned if I have to live with it.

    We actually have a covered place he could have parked in, but I don’t know if that would’ve changed anything.

    Turns out that we have a mutual friend, and he told me the owner dropped $800 for chewed up wiring. Maybe I did him a favor.

  • avatar
    George B

    I’ve had trouble with roof rats climbing under the hood in the winter. So far they haven’t tried to eat wiring, but one brought acorns to the top of the battery as a snack and another died on top of the transmission. Cooked rat is disgusting!

  • avatar

    Years ago, Honda started offering a capsaicin-infused wiring wrap tape. Why not wrap it all in something like that? Here’s a Honda dealer’s listing for the Honda tape:

    And the Web site for an electronic mouse blocker (I have no idea whether they work). There’s plenty of other brands out there, too.

  • avatar

    Back in the day they only went for Subarus and it was such a well know issue that it made it into My Name is Earl where Joy comment that the Brat is in the shop, damn mice ate the wiring again.

  • avatar

    And I thought it was the darn kids all these years. Sorry, kids !

  • avatar

    As an isurance adjuster i deal with this all the time. This affects all makes and models. They’re more frequent in the winter time as critters try to keep warm. I looked at a prius once that had a huge nest of field mice. Chewed the wiring harness but got inside the blower and nested in the passenger area. They got in the headliner and chewed the foam. When the tech was disassembling the dash, one flew into his face. I saw manliest man with full sleeve tatoos shriek like a girl. When the car was gutted there was feces and urine everywhere. The owner begged me to get rid of it. Was able to get my boss to approve a discretionary total loss due to the car being a bio hazard, but man, totaling a car because of rats!

  • avatar

    Not just wiring – buddy of mine with a pair of late Saab 9-5s had critters chew through the fuel lines! Happened twice before his mechanic got smart and ran them inside of metal electrical conduit before putting it back together. Had it done pre-emptively when he bought the second one. And the fun part is that due to modern emissions regs, the lines are one-piece with the fuel pump, and the whole thing with labor is about $1200. Insurance paid both times – yeah for $0 deductible comprehensive.

  • avatar

    When I worked as an extended warranty claims adjuster I denied a claim from mice chewing through a wiring harness. When the angry customer called demanding that we cover it I explained to him that the contract covered mechanical breakdowns and did not cover damage from external causes. The customer proceeded to blow his top and yell at me “THE MICE WERE INSIDE THE CAR YOU IDIOT”. I don’t miss that job at all.

  • avatar

    Yep, not a new problem. I do not know about the wiring insulation on the cars of the last ten years or so. One related report that I heard was that fast food and coffee shop suppliers wanted to reduce the number of throw away plastic cups that ended up as litter. A process was developed to add cornstarch to the mix so normal bacterial action would break down the plastic in a few months. Leftover was tiny grains of plastic.
    A year ago I helped a friend with a 1990s Saab convertible. The powered top did not work. He was convinced it was a problem with a relay at the hydraulic pump under the back seat. I did some testing and found no electricity getting from the switch to the relay. After we removed the seats, carpet, seat belt buckles and other stuff, we found that rodents had got into a vinyl tube that contained wires next to the center tunnel. After repairing the wires the top went up and down when the switch was used.
    Altogether it took the two of us over six hours to fix it. I am sure it would have been a large bill at a repair shop.

  • avatar

    Also for those who mentioned cats. It depends on the cat. Right after we moved into the current house about 20 years ago we adopted a neighborhood cat. Within a few weeks there were no longer any signs of rodents anywhere. He would dig gophers out of the ground.
    He lived to be about fourteen. Not long after he died we adopted two cats from the SOs brother. One disappeared a few months later. The remaining one wants to hunt the critters, but is not good at it.
    So I have to set traps in the garage to varying success.

  • avatar

    When I was on the VW forums 10-15 years ago, this problem came up, and somebody found out that VW in Europe offered an actual factory anti-rodent wiring harness option (complete with a picture of an actual rat biting on a wire, right in the option brochure – imagine ever seeing that in this country!).

  • avatar

    I wonder if the wiring on a Tesla is covered with this stuff – might lead to some char-broiled rats and mice, and some lawsuits by the EPA or the Interior Department for violating the endangered species act – at least until Trump can drain the swamp of all the Obama holdovers.

    • 0 avatar

      Same swamp, different reptiles. Pruitt is the swampiest of them all

      • 0 avatar
        30-mile fetch

        He’s made three thousand easily documented lies in a year and a half and they’re fine with it. Some are enthused. A subjective claim like “drain the swamp” isn’t going to be bothersome in that context. After all, he never did say he wouldn’t replace it with a swamp of his own liking.

        • 0 avatar

          Were any of the lies in your dream world whoppers like the ones Obama told to destroy our healthcare system? Were they told in an effort to nuclearize Iran? Were they told make people hate one another irrationally?

Read all comments

Back to TopLeave a Reply

You must be logged in to post a comment.

Recent Comments

  • dal20402: I leased one of these Civics (a 2006 EX manual) for three years. It was basic transportation that was...
  • bd2: This move to only-AWD is likely a temp move until the arrival of the RWD models (FWD is not seen as...
  • bd2: Biggest problem for Mazda has been its packaging. The longer hoods look nice, but the vast majority of buyers...
  • bd2: Mazda isn’t going after H/K, but rather the FWD Japanese lux brands (giving them a RWD alternative for...
  • bd2: The toned down beak was better than the simply awkward shape they are using now.

New Car Research

Get a Free Dealer Quote

Who We Are

  • Adam Tonge
  • Bozi Tatarevic
  • Corey Lewis
  • Mark Baruth
  • Ronnie Schreiber