You can protect your car against rats invading your car engine bay by installing Varna Ultrasonic Rat Repellent. It does not interfere with any of your engine wiring or accessories.
Place the repeller facing the hood and fix it using plastic tags and frame. The ultrasonic sound will bounce back evenly when faced opposite the hood.
Connect Red wire to Positive terminal and Black wire to negative terminal. The unit will start functioning.
For initial days, you have to stick the metallic sheet provided in the package to the hood when there is heat and sound absorbing pad is within the hood. This will help to reflect 100% ultrasonic sound throughout the engine bay.