In a home with an attached garage, the walls that separate the garage from the house should be constructed so that it is fire resistant. The idea is that carbon monoxide fumes, along with heat, smoke and fire can stay isolated inside the garage long enough for help to arrive and to give time for any occupants inside the home to be able to escape. The door leading to the inside of the house should be fire rated and of certain thickness and self closing. These doors should have weather stripping to keep the areas as airtight as possible. The walls should not have penetrations that would compromise the integrity of the wall and what it is designed to do.