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Yes, technically. The Mr. Heater Buddy series burns propane, and any propane combustion produces some carbon monoxide as a byproduct. What matters in practice is that the Buddy line is built with an oxygen depletion sensor (ODS). It’s specifically there to stop that CO from ever building up to a dangerous level in a normal, correctly used setup.
Why "Produces Some" Isn’t the Same as "Dangerous"
Nearly every fuel-burning appliance produces some carbon monoxide during normal combustion — a gas stove, a gas furnace, a propane grill. The question that actually matters for safety is whether that CO can build up to a harmful level in the space you’re using it. That’s precisely what the ODS is designed to prevent. It reads oxygen levels in the room and shuts the gas valve off once oxygen drops toward an unsafe threshold. That stops combustion before CO has a chance to build up from the incomplete combustion that starts as oxygen runs low.
Which Buddy Models Have This Feature
The Little Buddy, Buddy (formerly Portable Buddy), and Big Buddy are all built and certified with an ODS as standard equipment. That’s the feature that qualifies the entire lineup as indoor-safe in the first place. Our Mr. Heater Buddy series guide covers the differences between models. Our best Mr. Heater Buddy model roundup ranks them by aggregated owner reviews.
When the Risk Actually Increases
The ODS reduces risk substantially in a well-maintained unit used within its rated room size. But it doesn’t eliminate every scenario. Real risk goes up if you run a Buddy heater in a space far smaller than its minimum rated room size, with a malfunctioning or tampered sensor, or without following the manual’s ventilation guidance. None of these are the heater "failing" in a normal sense. They’re the safety margin narrowing because of how it’s used.
Why a Detector Is Still Recommended
Even with a working ODS, a battery-backed carbon monoxide detector is standard safety advice for any space running a Buddy heater. It’s a backstop for the edge cases the sensor doesn’t cover: sensor malfunction, tampering, or a space that’s genuinely too small for the model being used. See our does a propane heater need a carbon monoxide detector answer for the full reasoning.
The Bottom Line
The Mr. Buddy heater produces carbon monoxide the same way any propane appliance does. But its oxygen depletion sensor is specifically engineered to stop that from becoming dangerous under normal, correctly sized use. Treat the ODS as the core safety feature it is. Back it up with a detector. Follow the manual’s room-size and ventilation guidance rather than assuming any indoor-rated heater is risk-free on its own.