If an exhaust leak is in a cabin heat exchange area, what hazard can occur?

• A. Carbon monoxide can enter the cabin and render occupants unconscious.
• B. No hazard beyond odor.
• C. Increases cabin air pressure.
• D. Improves cabin heating efficiency.

Answer: (A)

The main idea here is that an exhaust leak in the cabin heat exchanger can allow toxic exhaust gases to enter the cabin. Carbon monoxide, a primary concern in this scenario, is colorless and odorless, so occupants won’t notice it without a detector or symptoms. CO binds strongly to hemoglobin, which reduces the blood’s oxygen-carrying capacity. That can lead to headaches, dizziness, confusion, fainting, and, with higher exposure, unconsciousness or death. So the real hazard is CO poisoning, not just an odor or a change in cabin pressure or heating performance.