What CO Sensor Standard Do I Need on a Generator?

What is ANSI/PGMA G300-2018?

ANSI/PGMA G300-2018 is a voluntary safety standard developed by the Portable Generator Manufacturers' Association (PGMA) and approved by the American National Standards Institute (ANSI). It specifies requirements for a carbon monoxide (CO) shutdown system on portable generators. Under this standard, a generator must be equipped with a sensor that detects elevated CO levels in the surrounding air and automatically turns the engine off before concentrations become hazardous.

The U.S. Consumer Product Safety Commission (CPSC) has long warned that portable generators produce dangerous levels of CO. The CPSC states that a single generator can emit as much CO as hundreds of cars, and that CO can incapacitate and kill within minutes. The PGMA G300-2018 standard is one of the voluntary measures manufacturers can adopt to address this hazard. The Federal Register notes that both PGMA G300 and UL 2201 (a similar standard) are assessed by CPSC for their effectiveness.

Because the standard is voluntary, not every generator on the market includes a CO shutdown. You should specifically look for models that claim compliance with PGMA G300-2018 or UL 2201.

• PGMA G300-2018 includes automatic engine shutdown when CO reaches a preset level.
• It also requires a sensor that is unaffected by normal generator operating conditions.
• The standard is designed to work alongside outdoor placement requirements, not replace them.

Why a CO shutdown standard matters

Carbon monoxide is colorless, odorless, and poisonous. The CDC reports that it kills hundreds of people every year and sickens thousands more. Portable generators are a major source because people often run them indoors or too close to a home, even with doors and windows open. The CPSC explicitly warns: never use portable generators inside homes, garages, basements, crawlspaces, or sheds, and always keep them outside at least 20 feet away from windows, doors, and vents.

a CO shutdown system does not replace safe placement. No standard allows you to run a generator inside your house. The sensor is a second line of defense: if wind shifts or an exhaust leak directs CO toward an occupied space, the generator stops before the levels become deadly. When you choose a generator, verifying that it meets a recognized standard like PGMA G300-2018 gives you that extra margin.

The EPA also highlights that deadly levels of CO can build up quickly in enclosed or partially enclosed areas and linger for hours after a generator is turned off. A sensor that triggers a shutdown can prevent that buildup from continuing.

How to verify a generator meets the standard

There is no government database that lists every compliant model. The most reliable way is to check the generator's product labeling and the owner's manual. Look for a statement such as "Meets ANSI/PGMA G300-2018" or "Certified to UL 2201." Many manufacturers print this on the carton or on a label affixed to the generator frame.

If you are shopping online, the product page or specification sheet often lists compliance. You can also contact the manufacturer directly. Because the standard is voluntary, some generators without a CO sensor will not make any claim; if you don't see any reference to PGMA or UL 2201, assume the unit lacks a CO shutdown. The best CO sensor generators guide lists models that explicitly include this safety feature.

Remember that a CO sensor is not the same as a CO alarm for your home. The sensor is built into the generator; an alarm is a separate device you place indoors. The CPSC recommends installing battery-operated CO alarms on every level of your home and outside sleeping areas, even when your generator has a CO shutdown.

PGMA G300-2018 vs. UL 2201

UL 2201 is another voluntary standard developed by Underwriters Laboratories. It also requires a CO sensor and automatic shutdown. According to the Federal Register, CPSC evaluated both UL 2201 and PGMA G300-2018 when considering a mandatory federal safety standard for portable generators. The proposed rule (16 CFR 1281) discusses the CO emission rates and shutoff levels of both standards, but no final rule has been issued.

For a buyer, the practical difference is minimal: either standard indicates the generator has an automatic CO shutdown system. Some generators may claim compliance with both. If a model lists either one, it meets the core safety function.

If you are comparing two otherwise similar generators and one has a CO sensor and the other does not, you should strongly prefer the one with the sensor. The generator safety checklist article explains other essential practices, but the sensor is a key safety upgrade.

What to look for when buying

When you shop for a portable generator, prioritize models that explicitly state they meet PGMA G300-2018 or UL 2201. This is especially important if you plan to use the generator during emergencies, when you might be tired or distracted and more likely to place it too close to the house.

Also consider your intended use. If you are buying an inverter generator for camping or tailgating, the same CO sensor standard applies. The best portable generators and best inverter generators guides both filter for models with CO shutdown. For home backup, see the best home standby generators guide, but note that standby units are permanently installed and have different requirements.

Remember that no standard substitutes for following the CPSC and CDC guidance: always operate the generator outdoors, at least 20 feet from any opening, and keep a working CO alarm inside your living space. The generator carbon monoxide safety article explains these rules in more detail.

What to pick for your use

Questions

Is a CO sensor required on all generators?

No. There is no federal mandate in effect. PGMA G300-2018 and UL 2201 are voluntary standards. Some states have adopted their own requirements, but the safest approach is to specifically look for a generator that states it meets one of these standards.

How do I know if my generator has a CO sensor?

Check the owner's manual or the label on the generator. Look for phrases like 'CO sensor', 'CO shutdown', 'ANSI/PGMA G300-2018', or 'UL 2201'. If you don't see any of these, contact the manufacturer to confirm.

Can I add a CO sensor to an older generator that doesn't have one?

In most cases, no. The CO sensor is integrated with the engine control system to trigger automatic shutdown. Retrofitting a sensor to an older unit is not a simple DIY project and could void the warranty. A separate CO alarm for your home is still essential.

Does a CO sensor let me run the generator in the garage?

No. The CPSC and CDC are clear: never run a generator indoors, in a garage, or in an enclosed space, even with the doors open. A CO sensor only shuts down the engine after CO accumulates; it does not prevent dangerous exposure.

Are there any downsides to a generator with a CO sensor?

The sensor can shut down the engine if it detects elevated CO, even if you are outside and the wind is blowing exhaust toward the unit. This is a safety feature, but it means the generator may stop unexpectedly in certain wind conditions. You can usually restart it after the air clears.