Carbon monoxide detectors should be placed on each level of your home and near your bedrooms. You’ll want to install them at least five feet from the ground on the wall. If you have a garage, you should place one near that area as well, especially if it adjoins the house.  “A lot of times, even if you start a car with the garage door up and you back the car out almost immediately, you’ll have residual carbon monoxide lingering in the garage space,” explains Roydhouse. “If you’re heating your home with a forced air system, when that cycles on it creates negative pressure that will pull air from around a leaky door… [and] it can potentially pull carbon monoxide in and push it through your duct work, distributing it throughout your home.” Do not put the detector inside the garage though—just in the area of the house near it. You also shouldn’t put your detectors near the furnace room or any fuel burning appliances.