Carbon Monoxide: Cars, Generators & the Attached Garage
Spot it
A car warming up in the garage (even with the door open), a generator run in or near the garage during an outage, or no CO alarm on the garage side of the house.
Fix it
Never run any engine in the garage — not briefly, not with the door open. Generators go outside, at least 20 feet from the house, exhaust pointed away. Install a CO alarm (UL 2034) inside the home near the garage entry and on every sleeping level.
Check your address to see what the public records say about this for your home.
Safer swaps
What actually fixes this — the category to look for, not a brand we were paid to name.
CO alarm, UL 2034 (10-year sealed battery)
The non-negotiable device for any attached garage or generator owner
CO-shutoff portable generator (PGMA G300 / UL 2201 sensor models)
Newer generators shut down when CO accumulates
Our picks for this
The products we would buy for this are in our air quality guide.
Read next
Related product category: Air quality
Sources cited
Sources
- Portable generators alone cause an average of nearly 100 US carbon monoxide deaths a year — and CO from an attached garage seeps into the house — U.S. Consumer Product Safety Commission (incl. SaferProducts.gov), 2026 (how we check this source)
Every source we cite is checked against our criteria first — see how we check our sources.
Related checks
- Gas Water Heater & Furnace: Carbon Monoxide — The furnace and gas water heater are the appliance-side CO sources.
- Nursery Air: VOCs, Fragrance & Fresh Paint — CO alarms belong on every sleeping level, the nursery included.
- Carbon Monoxide Alarms (Whole Home) — Where to put CO alarms in the rest of the home, and how often to replace them.
- Attached Garage Air Getting Into the House — Garage air that gets into the house through the shared door and wall.
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