Ask The Beaverton Car Guy: Who’s that Under the Hood? Cars Can Make Attractive Homes for Critters

By Larry “The Car Guy“ Ferguson


Hello Beaverton Readers,

This month, I am writing about Joan from Beaverton who called me asking about possible reasons for restricted air flow from her 2016 Toyota Hybrid’s heating/AC vents. She also reported that her ‘Service Engine’ and ‘Check Engine’ lights were on.


At first I wasn’t so worried since it’s still a new car with only 12,231 miles and still under the Manufacturer’s warranty. But while the car looked perfect on the outside, you can imagine our surprise when we popped the hood and found that a rodent family had decided to make this beautiful new car its home! To make matters worse, there were chewed wires and rat droppings throughout the ductwork. It was not a trivial matter.

Using my handy diagnostic tool, I found that one of the sensors – a crucial one impacting the catalytic converter – was shot. The rats nest was on top of the manifold and after removing it I could see the remains of a chewed wire dangling off the sensor. It would have been a minor problem, were it not for the fact that the wire went under the manifold, requiring several hours of work as the top of the engine had to be removed.

Rodents and Cars

This car is just one of hundreds of thousands of vehicles that are damaged by rodents (Rats, Mice, and Squirrels) every year. The cost of repair is not covered by the manufacturer’s warranty and can run anywhere from $50 to thousands of dollars.

I helped Joan get to the Toyota Dealership on TV Hwy where we were told by the service manager that here in Beaverton more than 100 cars were brought to his dealership in the past year because of rodent damage to electrical systems.“ We had three cars just this week,” he told me, “some of the most expensive jobs were $1,000, but he has had electrical damage that exceeded $3,000 in one vehicle where the rodents chewed up the entire body harness.”

So what makes our vehicles attractive to rodents?

Cars, especially during the cold and wet months, are warm and dry. In many cars, the wiring harnesses under the hood comes with a soy-based insulation and to rodents, it’s a convenient food source. Other factors to consider are heat and smell. The service manager warns all his customers not to leave food or crumbs in the car. This includes sealed or unsealed bags like old fast food containers but especially nuts and dog food. Anything that smells sweet is a draw so beware of even sweet or food type air fresheners.

Once the Technician inspected the vehicle, he estimated about 10 labor hours to clean out the ductwork, which included the removal of dog food, nesting materials, urine and fecal matter. This repair was approximately $1300. The Engine wiring harness repair was about the same cost with parts and labor.

If you have a garage, use it!

Joan had mentioned that she parked her car in the driveway because her garage was full of “stuff”. After this experience however, I’m happy to report that her car has taken priority over “stuff” and now is allowed to park in the garage, safe from rodent home shoppers!

Thank You all for reading! Special thanks to all of you who have called or emailed about automotive advice. Interesting questions are always welcomed.

Larry’s specialty is locating cars, even hard to find cars, for everyday folk. He has been in the automotive industry for over 35 years and has several degrees in automotive technology. Email him at or call 503-930-1493