Maybe Subaru’s Soy-Based Wiring Is Too Eco-Friendly?

Rodents just can't resist the soy-derived wire coatings used in many Subaru vehicles. The chewed up wires are costing owners hundreds, and sometimes thousands of dollars in repairs but Subaru, like other automakers, insists this isn't a defect.

Subaru prides itself on its eco-friendliness. They claim to be America’s first zero-landfill automaker1, and have made the switch to a more environmentally friendly, bio-degradable wire coating that is derived from soy.

But just like showing up with a tofurkey at the holidays, not all earth-friendly changes are without consequences.

The Pros and Cons of of Soy Wire Coating

The most obvious benefit of coating wires in soy-based materials is it results in less plastic in the landfill or oceans. That’s a good thing!

And the soy-based materials tend to be cheaper than their plastic counterparts, saving the automaker money. Now theoretically they could pass those savings on to the consumers, but let’s just say one way or another that saving money is also a good thing.

However there are also downsides, depending on your perspective.

The coatings are a perfect chew toy for rodents, provide excellent nesting material, are are found in near endless supply in a warm, hidden spot. If you’re a mouse, it’s the greatest thing ever. But if you’re an owner waking up to a severed fuel line, it’s a little less enjoyable.

Subaru is not the only one to make this switch or deal with the rodent-problem

In January 2016, a lawsuit filed against Honda claimed the soy-based wiring was irresistible to rabbits. Later that year, a similar lawsuit was filed against Toyota. In July 2017, both Hyundai and Kia were sued for using soy wiring.

In each case, the automaker was accused of concealing the problem and/or refusing to fix the issue under warranty.

Story involves Lexus and Honda, but you get the picture

Replacing a fuel line or running new electrical wiring is not cheap

Typically owners report paying a couple hundred dollars for repairs, but that’s if they’re lucky. In some cases rodents have been known to chew through wiring harnesses or wires in the automatic transmissions, costing $2,433 and $1,200 to fix respectively.

Prevention options get really, really weird

Search the Internet for how to keep rodents away from your car and you’ll see everything from peppermint spray, to tape laced with capsaicin, to the less than desirable “coyote pee” option as explained in this Forbes article:

Every night, Joann’s pours a little coyote piss around her tires. “I dot my driveway with some too,” she says. She also places a  Coyote urine-soaked sponge inside a tin pan near the car. She’s not sure it’s working yet and does not want to take her car in for any more repairs until she’s rid of the rats once and for all.

If I had to do that every night it’d really piss me off.

Subaru Class-Action Lawsuit in Hawaii

In November 2017, Subaru joined the list of automakers sued for using soy-based wire coating. The lawsuit is filed in Hawaii and limited to a certain dealership, but the verdict may result in state-wide or nationwide action.

Plaintiff Joy Diane Shuey says she purchased a new 2015 Subaru Forester from Servco Subaru, but about a month later she took the SUV back to the dealer because of a fuel odor and an illuminated check engine light … The Servco technician allegedly discovered the fuel line and rear wiper hose needed to be replaced because they had been chewed by rats. Shuey says she paid $318.52 for repairs that Subaru didn’t cover under warranty.

So once again we’re seeing the same story line: automaker uses soy-derived products → rodents see their opportunity and cause damage → damage isn’t covered under the automaker’s warranty.

What really gnawed at the plaintiff was how later that month, she was charged $2,433.30 to replace an engine wiring harness that had been chewed through.

In general, Subaru’s response is the same as Honda, Toyota, and other manufacturers: this isn’t a defect, invest in some coyote pee, or maybe get a garage cat.

  1. From Subaru’s Own Environment page. 

Story Timeline

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What Owners Are Saying

“I turned my car on one afternoon and found the power steering warning light stayed lit on the dashboard. When I tried to drive, the power steering was completely gone ... Upon removal of power steering rack, technician found rodent damage on wiring to module on rack and pinion unit. Total repair cost was $2,800.”

2016 Impreza owner in VA

“Rodents destroyed a wire associated with my power steering. The car was towed to the dealer, and they provided a rental. The next night the same wire was destroyed by rodents ... Insulating automobile wires with soy, especially those wires related to safety equipment, is an engineering disgrace. Therefore, using the same product found in commercial rodent food to insulate vital automobile wiring is outrageous.”

2014 Crosstrek owner in CA

“Within 5 weeks of each other, a rodent has chewed through the wiring bundle to the low oil pressure sensor and fog lights of my 2016 Outback. Both were $500 repairs. The first was at about 1000 miles on the car. If the bundle has to be replaced, it is a $1350 repair. Subaru says not their problem.”

2016 Outback owner in CO

OK, Now What?

Maybe you've experienced this problem. Maybe you're concerned you will soon. Whatever the reason, you can help make sure it gets the attention it deserves.

  1. File Your Complaint is a free site dedicated to uncovering problem trends and informing owners about potential issues with their cars. Major class action law firms use this data when researching cases.

    Add a Complaint

  2. Notify CAS

    The Center for Auto Safety (CAS) is a pro-consumer organization that researches auto safety issues & often compels the US government to do the right thing through lobbying & lawsuits.

    Notify the CAS

  3. Report a Safety Concern

    The National Highway Traffic Safety Administration (NHTSA) is the US agency with the authority to conduct vehicle defect investigations & force recalls. Their focus is on safety-related issues.

    Report to NHTSA

  4. Contact Subaru

    Subaru Support

    Subaru Plaza P.O. Box 6000 Cherry Hill NJ 08034-6000 USA

    This site is not affiliated with Subaru.