Best Generators With Carbon Monoxide Shutoff

Why CO shutoff matters

Portable generators produce a lot of carbon monoxide. The U.S. Consumer Product Safety Commission estimates that portable generators are associated with an average of nearly 80 CO poisoning deaths each year. Many of those deaths happen when generators are run in garages, basements, or too close to the house during outages.

Generators with carbon monoxide shutoff have a built-in CO sensor. When CO around the generator reaches a dangerous level, the generator shuts itself off. It is not a substitute for proper placement and indoor CO alarms, but it is an important additional layer of protection.

The two certifications to look for

Two voluntary safety standards cover CO safety on portable generators:

• ANSI/PGMA G300: requires a CO shutoff system that turns the generator off when CO concentrations reach certain levels.
• UL 2201: requires both reduced CO emissions from the engine and a CO shutoff system.

CPSC staff analysis found that generators meeting UL 2201 would avert nearly all of the deaths in the incidents studied, and those meeting PGMA G300 would avert about 87 percent. The difference comes largely from UL 2201's reduced-emission requirement. For the full breakdown, read our explainer on UL 2201 vs PGMA G300.

Manufacturers usually mark compliance on the packaging and in product descriptions. Look for the standard name, not just a vague "CO safety" claim.

What to look for beyond CO shutoff

• Certification: UL 2201 or PGMA G300, clearly stated.
• Indicator lights: a warning light that explains why the generator shut down, so you know it was CO and not low oil or fuel.
• Inverter or low-THD output: clean power for electronics.
• Dual fuel: flexibility for long outages.
• Transfer switch outlet: a 30-amp or 50-amp locking outlet for home connection.
• Electric start.

Our picks by category

How CO shutoff works

A CO sensor near the generator measures carbon monoxide concentration. When levels exceed a threshold, either an instantaneous high reading or an elevated average over time, the system shuts down the engine. The generator typically indicates the reason with a light. After a shutdown, move the generator to a safer location before restarting. Never restart it in the same place.

Existing generators without CO shutoff

If you own an older generator without CO shutoff, you do not need to discard it, but be extra careful:

• Place it well away from the house.
• Install CO alarms on every level and outside sleeping areas.
• Consider a standalone CO detector designed for generator use near the generator. See our guide to generator CO detectors.
• Plan to upgrade to a certified model when you replace it.

Regulatory status

CPSC began rulemaking on portable generator CO hazards in 2016 and published a supplemental proposal in 2023. As of our most recent check, a mandatory federal rule has been proposed but not finalized. The voluntary standards remain the main benchmark. Check CPSC for the current status.

Placement is still the most important step

Even with CO shutoff, where you put the generator matters most. Keep it outdoors, away from the house, and protected from rain and snow with a cover rated for use while running, not by moving it into a garage or under a porch.

Buying checklist

Before you buy, confirm these in the product listing or manual:

1. Standard compliance: "Complies with ANSI/PGMA G300" or "certified to UL 2201" stated clearly.
2. Running and starting watts: enough for your essential loads with headroom.
3. Outlet types: a locking 30-amp or 50-amp outlet if you plan to use a transfer switch or interlock.
4. Fuel type: gasoline only, or dual fuel for propane flexibility.
5. Noise level: inverter models are much quieter, which matters for neighbors during long outages.
6. Parts and service: a brand with accessible service centers and replacement parts.

Common questions about nuisance shutoffs

Some owners worry that CO sensors will shut the generator down unexpectedly. A shutdown means the sensor detected elevated CO around the generator, which usually means it is too close to a wall, in a partially enclosed space, or in a spot where exhaust collects, such as a corner or under an overhang. Treat any CO shutdown as a warning to move the generator farther out into open air.

Wind can also blow exhaust back toward the generator in some locations. If shutdowns happen repeatedly, try a more open location with the exhaust pointed downwind and away from the house.

Why emissions reduction matters

A shutoff system reacts after CO has built up. Reducing emissions at the source means CO builds up more slowly in the first place, which gives people more time to notice and escape if a generator is misused. That is the main reason CPSC staff found UL 2201 more protective in their simulations. For more detail on the standards, read our UL 2201 vs PGMA G300 explainer.

Pairing a generator with indoor alarms

Think of CO safety in layers: correct placement outdoors, a generator with CO shutoff, and CO alarms inside the home. Each layer covers weaknesses in the others. Interconnected alarms, where one sounding triggers all of them, add another layer of protection in larger homes.

CO shutoff on inverter vs conventional generators

CO shutoff is available on both inverter and conventional open-frame generators, across many sizes. Inverter models tend to be quieter and more fuel-efficient at partial load, which suits long outages with light loads. Conventional models deliver more watts per dollar for larger loads. Choose the type based on your power needs, then filter for CO shutoff certification.

Renting a generator

If you rent a generator during a storm, ask whether it has CO shutoff and which standard it meets. Rental fleets may include older units without it. Whatever you rent, follow the same rules: outdoors only, far from the house, with CO alarms inside.

Placement quick reference

• Outdoors, in open air, at least 20 feet from the home per CPSC guidance.
• Exhaust pointed away from doors, windows, vents, and neighbors' homes.
• On a stable, level surface, protected from rain and snow by a cover rated for use while running.
• Never in a garage, basement, crawlspace, shed, or under a carport or porch roof.

Store the manual with the generator

Keep the owner's manual, including the section explaining the CO shutoff indicator lights, in a zip bag with the generator. During a stormy night is not the time to search online for what a flashing light means. Knowing whether a shutdown came from CO, low oil, or overload tells you exactly what to fix before restarting.