General Question

crisw's avatar

Rats chewing car wiring- any ideas on preventing it?

Asked by crisw (14116points) April 12th, 2009

I live in the country. When I look out my window I see 100 acres of chaparral, and beyond that, 200 acres of hay farm, and beyond that, a wildlife refuge with thousands of acres of more chaparral. Thus, we have an endless supply of rodents.

Over the last 7 years, the rats caused thousands of dollars of damage to my ‘99 Tacoma. It was, however, not a very sophisticated car, and there was only so much wiring for them to chew. I just moved up to a 2007 Mitsubishi Outlander last week, and already the rodents are storing nesting material under the hood. Aaargh! This car has a lot more wiring to chew, and it would be a lot more expensive to fix the damage.

So here are some things we have and have not tried-
Cats- Nope, they’ll be coyote bait.
Garage- Don’t have one.
Traps or poison- Futile, even if I didn’t have ethical problems with them. There are thousands more where these came from.
Mothballs, ammonia, cayenne pepper- They seem to have weak effectiveness. However, they also stink up the car, and you have to remember to remove them from the engine block before driving! What research I can find on them shows that rodents habituate to them and they do not work long-term.
Lifting the hood and hanging a light- I’m going to try this, but, of course, only some of the engine compartment will be illuminated, so I don’t think it’s 100% effective.
A fan- Another one I am going to try- it’s been suggested that the noise and vibration will scare them off. I think they may also habituate to it, though.

Anyone else have any great ideas?

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37 Answers

filmfann's avatar

Coyote urine placed on the ground below where you park your car might help.
Also, there are ultrasonic devices that give rats headaches, and they abandon the area after a day or two.

The_Compassionate_Heretic's avatar

You can either find where the rats are coming from or you could try finding what the rats are attracted to and remove it.

You may want to check around the online auto forums. It’d be surprising if no one had ever had a similar problem to yours.

AstroChuck's avatar

Get a cat to live in your car.

The_Compassionate_Heretic's avatar

Where do you get coyote urine anyway?

filmfann's avatar

Coyote urine available at hardware stores, in the pest control section.

The_Compassionate_Heretic's avatar

Somewhere in the world, there is someone collecting coyote urine who is seriously reconsidering their occupation.

RedPowerLady's avatar

Here is an alternative idea. Figure out what the rats would rather chew on and put it somewhere else, away from your car. You might have to leave a trail of treats to lead them there the first few times but after that they will just go straight to the source.

I’m not sure that’d be 100% effective but it might be worth a try.

RedPowerLady's avatar

Also I just read that the predatorpee thing may work.

rooeytoo's avatar

We have the same problem here and ant spray seems to work on the ants and the rats. Also they come here because water is available, I have to empty the bird bath at night. I hate to use the spray but I hate it when the car won’t start and it costs a fortune to repair their damage. If you come up with a good non toxic solution, please pass it along.

crisw's avatar

We have plenty of real coyote urine- we have several coyotes that frequent our yard. I think the rats are used to it. :>) And, unfortunately, the ultrasonic devices have been proven not to work in many studies.

crisw's avatar

The rats are coming from thousands of acres of prime habitat, as I mentioned in my lengthy “More” section.

I’ve read all the auto forums I could find; their suggestions are included in my “More” list.

Unfortunately, coyote urine is not obtained in coyote-friendly methods :>( It’s from trapped or fur-farmed coyotes.

crisw's avatar

Do you spray the ant spray on the engine?

rooeytoo's avatar

We spray the entire engine compartment including the engine with it. We buy a litre of it in a hand pump bottle. Knock on wood has been working well so far, but it is usually more of a problem for us during the dry and that is just starting. Do you have water standing, get rid of that as well, seems they come for a drink and stay for dinner.

westy81585's avatar

You could build a garage?

AlfredaPrufrock's avatar

There’s some good solutions on here, including:
Hanging mothballs in stockings inside car hood
A solid rodent poison bars, “Just One Bite II,” with Bromadiolone.

WifeOfBath's avatar

Lavenderoil very strong mice and rats hates this…:)
and found this, for you to read…..

Lupin's avatar

Your situation sounds like mine about three years ago. The light under the hood does not work. It only makes a nice warm spot that attracted mice – into the air cleaner.
They were in the house, in the barn, in the car…. Been there, done that, tried all the nontoxic deterrents. Our neighborhood was also blessed with do-gooders from the surrounding area tipping out their HavaHart 1040 traps across the street, changing their problems into ours.
The only thing that finally worked was getting mad and starting an aggressive elimination campaign followed up with a maintenance schedule. Cracked corn doped with 2–3% ZnP placed in the car will drop them where they sit. Check the vehicle daily. The green warfarin blocks or pellets will take about 4 days to work. Unfortunately, you will find and smell the little surprises everywhere. I also used traps – the permanent kind. Lots of them. Probably spent $100 for everything. The effort took about 1 month but it finally worked. (This is the season to get busy by the way.)
I discussed this in a previous post . Good luck.

I don’t know where you live or your prevailing climate but, are you sure they are rats? Did you verify either visually or by finding the droppings? You might have other rodents: mice, chipmunks, squirrels, etc. They are just as irritating and destructive. The solution is basically the same. Only the bait size will vary.

jrpowell's avatar

What about strobe lights under the car? I have heard of them being used to keep them out of attics.

Dog's avatar

@JohnPowell Yes- I have heard the strobe lights work. Basically the rats are too busy dancing to chew. I might add that if this does not work one could try playing Barry Manilow cd’s ;)

Crisw I wish I had a serious solution for you. I lived in a rural area and know your frustration.

Sadly areas such as you describe are a no- go for outdoor cats. The problem you describe is the result of an imbalance of natural preditors.

I do know that strobe lights drive me nuts so possibly the illusion of movement would deter so long as the lights did not provide the heat the rodents seek.

I will research a bit and see if I can find anything else you have not tried.

crisw's avatar

No poison here, thanks. We have far too many native predators- owls, hawks, bobcats, coyotes, etc. plus far too many non-target critters like ground squirrels, jumping mice, and white-footed mice. And, as I have explained, there is simply no way that I could kill all of the rodents, even if I wanted to- there is just too much habitat out there for them.

And yes, they are definitely rats- a few of them met an untimely end in the fan blades of my Toyota, so I saw the culprits.

filmfann's avatar

@johnpowell, @Dog You should be advised that many states outlaw the simulatious use of strobelights while playing Barry Manilow.

crisw's avatar


Hmmm…maybe that will do the trick! We don’t have any neighbors nearby :>D

crisw's avatar


Interesting…but the link you provided was actually to a study that showed that lavender oil had calming effects on rats! I would rather have an odor deterrent that makes them think that every cat, owl and coyote in our neighborhood is living under my engine block :>)

Dog's avatar

I have been researching your plight and have found the following quotes that may or may not help:


“Rats have acute hearing and can readily detect noises. They may be frightened by sound-producing devices for awhile but they become accustomed to constant and frequently repeated sounds quickly. High-frequency sound-producing devices are advertised for frightening rats, but almost no research exists on their effects specifically on rats. These devices must be viewed with considerable skepticism, because research has not proven them effective.”

“Lights (flashing or continuously on) may repel rats at first, but rats will quickly acclimate to them.

I have found articles that offer a variety of suggestions to repel rats. Because these are
relatively cheap to try and possibly worth a shot I will post them here:

1. Peppermint oil (not extract) the theory is that the rats do not like the smell and will avoid it. I would assume sprinkling it around the engine cavity may also cause the scent to drift into the car so if you do not like peppermint I would not suggest it.

2. Bounce dryer sheets- the original scent. For the same reasons as stated above. Put them in the engine away from moving parts or parts that will be hot.

Also worth a shot and cheap to try: I have a friend who works around the country and travels in an RV. He told me that he always brings Ajax scouring powder with him and spreads it out under his RV before parking. He claims that it deters both rodents and ants.

Take all the suggestions above with a grain of salt and a hint of optimism.

crisw's avatar

Thanks. They might be worth a try- at least peppermint oil and Bounce dryer sheets smell better than coyote urine and mothballs! Perhaps, if the scents are switched out so the rodents don’t acclimatize to them, they might be effective- worth a try!

Lupin's avatar

During my futile non-lethal period, I bought containers of cayenne pepper from Sam’s and spread it around thinking it would deter critters. Even that was not effective. I sprayed with WD-40 and just made a mess. Nature pushed me over the edge.
By the way, I do love the area. That’s why we moved out here. I just wanted outside critters to stay outside where they belong.

AlfredaPrufrock's avatar

@Dog, I wondered about sound. The blueberry farm I go to uses sound to keep birds off the bushes.

What about bars of Irish Spring soap?

FiRE_MaN's avatar

i know to keep caterpillers off of roses and what not they spray the plant with soapy water which in turn makes the plant taste like soap, a taste i know to be unpleasant >_< so many you can get a spray bottle and fill it with soapy water and spray the wires. it might work and it might not but it would be cheap to try.

Dog's avatar

@FiRE_MaN the premise is good but one would have to be very careful not to damage the electrical. Also soap leaves a residue that would pick up dirt. It works great on aphids on my roses though.

@AlfredaProfrock Interesting about the blueberry farm. The airports nearby have a cannon type sound that randomly goes off to scare the birds off.
I have no idea about the Irish Spring soap. Now I wish I had a rat to experiment with.

FiRE_MaN's avatar

@dog yeah thats what i was worried about too but it depends where the wires are and what they are for and if they are bitten already. If they are wures under the hood i think it would be fine since they are made to be exposed to rain and snow.

RickSuddes's avatar

To stop chewing rats & squirrels spray Rataway Fragrance. Rataway fragrance is non-poisonous and non-toxic. safe around service personal, children and pets.

davidthompson20's avatar

There are good answers here for mice or rats in your car.
Basically, the scents (coyote pee, bounce, mothballs) do not work. Poison only gets you a smelly dead rodent somewhere you can’t get it out. The only real defense is to set traps below the wheels, in the car, and to deny them food and water and cover near your car.

stonerjohna's avatar

why don’t toyota change insulation on wiring using platic instead of rubber

Response moderated
Aster's avatar

They get worse in winter. We had them tear up an RV parked outside. We were picking the acorns out of the engine and a cute rat looked at me with blue eyes, I screamed and said I’m finished .
We put rat poison pellets out all the time, some worked, but many more would be born. Then they got under the hood of the car.
The RV continued to run with ruined wires, for some reason, but we sold it and the buyer replaced lots of wires.
It appears that vehicles have to be in tightly sealed storage if you live in the woods like we did, which I miss.

panahead's avatar

i also have a cabin in a area that is full of mice… we are not there full time so it makes it hard to keep up on trapping them and also to have a cat…. i have tried all of the above… coyote pee… cayenne pepper… moth balls… rat bait… traps… etc… etc… i think that you have to aggressively trap them with old school wooden rat traps baited with raisins… but… if you are not there all the time then i have found that if yopu circle your vehicle with a ring of flashing… it is a thin metal that is used for roofing and it comes in a vaeriety of sizes… pick one that is aprx. 12” tall and place it around your vehicle… the mice are unable to scale it…. good luck and let me know if you find a better answer…

kyleaz's avatar

We have 2 research facilities here in Arizona. After you have tried all the urban legends and figure out they don’t work very long people will get serious and do a lot of research on rats chewing wires in cars. After 100 of hours of DVD full of rodent research we tested many product to see what worked and what didn’t.
Please DO NOT use a poison. They can kill family pets and doesn’t work for pack rats. Their biology has evolved so that it doesn’t work. They will get ill and slow down letting predictor birds hunt them down easier and then they die after eating the rodent. That is why we have declining numbers of hawks,owl and other great birds.
Using a snap trap animals will chew their body parts off to get free of the trap. I prefer the use of a Have A Heart type live trap.
Many ultrasonic devices also do not live up to what they claim. Forget predictor urine, in our lab settings it was used as a litter box…
This is a problem with almost all models of cars not just one or two. Rodents do not prefer a certain wire or color.
If you go to you can see the new technology that has been invented by an aerospace engineer and a biologist. The devise is sold in over 50 stores and shipped all over. It is green, safe, made in the US and guaranteed for 6 months.
There is also a live person on the technical support phone line and can help with any problems.
We are very happy with this product and has been used happily by 1000’s now. It works on tractors, ATVs. campers and RV’s A smaller unite keeps rodents out of the BBQ grills and spa wires. There is also a 24 volt model for special RV’s
This is just a truly better mouse trap that keeps the critters packing!
One big major warning in the South West please be careful of rodent droppings. THe rodents carrie the Hunts VIrus and people have now died from it. You gloves and a mask to clean up droppings.

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