What is a CO sensor (CO shut-off) on a generator?

Generator exhaust contains carbon monoxide (CO). You can't see it or smell it, and it kills people every year during outages. A CO sensor is a safety feature that shuts the generator off when CO builds up around it. It's one of the most useful features a generator can have, and it's a hard rule on this site: we only list gas generators whose maker says they have one.

What a CO sensor does

It's a small sensor built into the generator. While the engine runs, it checks the CO level in the air around the machine. If the level gets dangerous, it shuts the engine off. It's automatic, a bit like the low-oil shutdown most generators already have. Both inverter generators and conventional generators can have one.

Westinghouse describes it this way: the system "continuously monitors air quality near the generator and automatically shuts down if dangerous CO levels are detected." Champion says CO Shield "monitors the accumulation of carbon monoxide" and "automatically shuts off the engine" if it detects unsafe levels.

What makers call it

Different brands use different names for the same idea. From the makers' own pages:

Maker	Name on the spec sheet
Champion	CO Shield® carbon monoxide auto shutoff
WEN	Watchdog CO Shutdown Sensor
Westinghouse	CO sensor (for example, the iGen5000DFc)
DuroMax	CO Sensor Shutdown

Other brands use their own names. Look for a maker statement that the generator shuts itself off when CO builds up. "Low CO" or "low emission" alone is not the same thing.

PGMA G300 and UL 2201

Two safety standards now cover CO on portable generators:

• PGMA G300-2023 (ANSI/PGMA G300), from the Portable Generator Manufacturers' Association.
• UL 2201-2023, from UL.

CPSC's May 2026 release urges buyers to look for a CO shut-off feature. It says models certified to the latest PGMA G300-2023 and UL 2201-2023 standards "include carbon monoxide safety technologies designed to significantly reduce CO poisoning risk." Champion's product pages, for example, say the model meets ANSI/PGMA G300.

Is it required by law? Not by a federal rule, as of October 2026. CPSC proposed a mandatory standard and published a supplemental proposal in April 2023. We found no final rule. So these standards are voluntary. Check the spec sheet or manual for the certification.

Why it doesn't make indoor use safe

This is the most important part. A CO sensor is a backup. It's not a reason to bend the rules.

• It only senses CO at the generator. CO can drift through a door, window or vent into your home well before the sensor trips. People inside may be breathing it.
• It reacts after CO has built up. By then, a garage or porch already has dangerous air.
• The maker says so. Champion states that CO Shield "is not a substitute for an indoor carbon monoxide alarm or for safe operation."

So the rules don't change. Run the generator outdoors only, at least 20 feet from your home, with the exhaust pointed away from windows, doors and vents, CPSC says. Never in a garage, basement, shed or on a porch, even with doors open. Keep battery or battery-backup CO alarms on every level of your home. Our carbon monoxide guide has the full checklist.

If the CO sensor shuts your generator off

Treat it as a warning. CO built up around the generator.

1. Check on people first. Headache, dizziness, nausea or confusion can mean CO poisoning. Get everyone into fresh air and call 911.
2. Don't restart it in the same spot. Move it farther out into open air, 20+ feet from any building, away from walls and overhangs.
3. Read the manual. Follow the maker's steps for restarting after a CO shutdown.

Never disable, cover or bypass the CO sensor. If you think it's faulty, contact the maker or an authorized service center.

Prefer no exhaust at all?

A battery power station has no engine and makes no CO. It's handy for a fridge, CPAP and phones. See portable power station vs generator.

Safety: Run it outdoors only, 20+ feet from the house, away from windows and doors. Read our carbon monoxide guide.