Rat

Same thing has happened in my 2016 Prius, in the same spot! Looks like a warm spot for critters to chew and nest. Be very careful! They will chew through wires and cause expensive damage to the car’s computer systems. This happened to my friends Prius prime $7000 damage. I’ve been scouting my engine bay daily, try the Irish Spring soap trick, and sprinkling peppermint oil into the engine bay and the mentioned underliner.

 

Over the years, my dad and my uncles have used petroleum based rustproofing in these areas. While rodents will chew on soy or plant based insulation on wires, they do not, if they have been coated with a petroleum based product.

Also, applying a peppermint oil based rodent repellent and letting it dry completely before applying rustproofing and then re coating it again assures additional protection.

I've also seen rodent repelling rustproofing.

 

throw some irish spring soap around the car. Purely anecdotal but doesn't hurt to try. Also leave some much traps around.

 

Mostly sun and heat insulation.

 

Anecdotal evidence is that rodents chew on wire harness coverings, perhaps on the wires themselves. The evidence I found on my vehicle is on the plastic undercarriage plates that cover the bottom of the car. Presumably to increase aerodynamics and fuel efficiency. The plastic plate below the engine has a insulation pad, filled with a soft fiber like a pillow. It has been chewed, a pile like a nest was retrieved from the engine bay.

 

I just noticed exactly same issue in my prime. What did you end up doing as a deterrent?

 

I found the same type of white fluffy material on the floor of my 2017 Prius engine compartment, plus rat droppings on the components above. I live in an apartment and my assigned parking spot is right next to the neighbor's garbage bins, so I have no way to solve the rat problem except whatever I can do in my engine compartment. I would prefer a mechanical deterrent over a spray that poisons the critters. And I don't really want to suck toxins or petroleum products into my air intake. Has anyone had success with Ultrasonic Rodent Deterrents? I am looking at Loraffe because it is ultrasonic but also has strobe lights. Trouble is, I am concerned that it will drain the 12 volt battery. I just replaced mine yesterday.

 

When we were Traveling full time in our RV we would get fresh peppermint sprigs to keep critters out of the under carriage and compartments. Worked very well and was all natural.

 

Try the rodent deterrent tape (see the last paragraph of that posting).