You’re staring at that shiny new Series 10 on your wrist, or maybe you’re hovering over the "Buy" button on Apple’s website, and you notice something weird. Or rather, you notice something gone. If you’re in the United States, that little red-and-blue icon for the Blood Oxygen app is either a ghost or a non-functional shell. It’s frustrating. Honestly, it’s a bit of a mess for a device that costs several hundred dollars and markets itself as the ultimate health companion.
The Apple Watch 10 blood oxygen situation isn't a hardware failure. It isn't because the sensors aren't there—the LEDs and photodiodes are physically tucked into the back of that sapphire crystal. They just don't work. This whole saga is the result of a high-stakes legal war between Apple and a medical tech company called Masimo.
Why your Apple Watch 10 blood oxygen sensor is currently "off"
Let's get into the weeds of the Masimo dispute because it’s the only way to understand why your watch is nerfed. Masimo, led by CEO Joe Kiani, sued Apple claiming they stole trade secrets and infringed on patents related to pulse oximetry. Specifically, they argued that Apple’s method of shining light through the skin to measure oxygen saturation ($SpO2$) was their intellectual property.
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The International Trade Commission (ITC) actually agreed.
By early 2024, the ban was in full effect for any watches Apple sold directly. To keep the Series 9 and Ultra 2 on the shelves, Apple had to disable the feature via a software lock. When the Series 10 launched, it inherited this legal baggage. If you buy an Apple Watch Series 10 today from an official retailer in the U.S., the blood oxygen feature is hard-coded to be inactive. It’s a software "lobotomy" performed to satisfy a court order.
Interestingly, this is almost exclusively a U.S. problem. If you hop across the border to Canada or fly to London, the Apple Watch 10 blood oxygen features work perfectly fine. The sensors are identical. The silicon is the same. The difference is purely a digital fence built around the United States.
Is the Series 10 hardware actually different?
People keep asking if Apple changed the sensors to get around the patent. They didn't. Not yet, anyway. Apple’s engineering team is likely working on a "non-infringing" way to measure blood oxygen, but for the Series 10 launch, they stuck with the existing architecture.
The Series 10 is thinner. It has a bigger OLED screen. It charges faster. But the health sensor array on the bottom looks strikingly similar to the Series 9. Because Apple is still appealing the ITC ruling, they are playing a waiting game. If they win the appeal, they could theoretically flip a switch in a future watchOS update and suddenly your Apple Watch 10 blood oxygen app would spring to life.
But don't bet your mortgage on that. Legal appeals can take years.
Does the missing sensor matter for sleep apnea tracking?
This is where it gets confusing for the average person. Apple heavily marketed the Series 10 as a tool for detecting Sleep Apnea. Usually, sleep apnea detection is closely tied to blood oxygen drops (desaturations) during the night.
Guess what? Apple’s sleep apnea notification feature on the Series 10 doesn't actually use the blood oxygen sensor.
Instead, it uses the accelerometer. It tracks something called "Breathing Disturbances." The watch looks for tiny, microscopic movements in your wrist that indicate a disruption in your normal respiratory patterns. If these disturbances happen frequently over a 30-day period, the watch flags it.
So, you can still get sleep apnea alerts on a U.S. Apple Watch 10, even though the blood oxygen sensor is dead. It’s a clever workaround. However, many medical professionals argue that $SpO2$ data is a vital piece of the puzzle for understanding sleep quality. Without it, the Series 10 is essentially fighting with one hand tied behind its back.
The accuracy debate: Was it ever a medical device?
Apple has always been careful with their wording. They call it a "wellness" feature. They explicitly state it is not for medical use.
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Masimo, on the other hand, makes hospital-grade pulse oximeters. Their argument is that Apple’s "consumer-grade" sensor wasn't just infringing on patents, but that it wasn't reliable enough for clinical decisions anyway. There’s some truth there. Wrist-based pulse oximetry is notoriously finicky. If your watch band is too loose, or if you have certain skin tones, or if your wrist is cold, the readings can swing wildly.
Even when the Apple Watch 10 blood oxygen sensor is active in other countries, it’s meant for "spot checks" or background readings during sleep. It isn't a continuous, medical-grade monitor. If you have a serious condition like COPD or severe asthma, a $15-20$ finger pulse oximeter from a drugstore is almost always more accurate than a $400$ smartwatch.
Can you bypass the restriction?
I've seen people on forums suggesting you can just use a VPN or change your Apple ID region to get the blood oxygen feature back.
It doesn't work.
The restriction is tied to the specific model number of the watch. When a Series 10 is manufactured for the U.S. market, it is assigned a part number that tells the software to permanently disable the blood oxygen app during the initial pairing process. Even if you take that watch to France, the feature will remain disabled.
The only way for a U.S. resident to get a working Apple Watch 10 blood oxygen sensor is to buy the watch physically outside of the U.S. (like in Canada or Mexico) and bring it back. Because those watches have "international" part numbers, the feature stays active even when used on U.S. soil. It’s a weird loophole, but it’s the reality of the current patent landscape.
What should you do if you need oxygen tracking?
If you genuinely need to track your blood oxygen for health reasons, the Apple Watch 10 might not be your best bet right now—at least not if you're buying it in America.
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You have a few options:
- Look at Garmin or Samsung: Their patents are different, and their blood oxygen features are fully functional in the U.S.
- Buy an older "New Old Stock" Series 8: Any Apple Watch sold before the ban (January 18, 2024) still has functional blood oxygen. If you find a brand new Series 8 or an early Series 9 that was sitting in a warehouse, the feature will work.
- Use a dedicated device: Buy a ring like the Oura or a dedicated medical-grade pulse oximeter.
Honestly, it sucks that such a premium piece of tech is crippled by a legal fight. Apple is a $3$ trillion company, and Masimo is a titan in the medical space. They're bickering over billions while the consumer gets a product with a "Coming Soon" sign taped over one of its best features.
Maybe the Series 11 will have a totally new sensor that sidesteps Masimo’s patents. Maybe Apple will just pay the licensing fee (unlikely, given Tim Cook’s history). For now, the Apple Watch 10 blood oxygen feature is a ghost in the machine for U.S. users.
Actionable Steps for Potential Buyers
If you are currently deciding whether to pull the trigger on the Series 10, follow these steps to ensure you aren't disappointed:
- Check your region: Confirm you are buying from a region where the feature is enabled if $SpO2$ is a dealbreaker. If you are in the U.S., assume it will never work on the device you buy today.
- Evaluate your "Why": If you want the watch for sleep apnea notifications, go ahead and buy it. The Series 10 uses the accelerometer for this, so the lack of an oxygen sensor won't stop those alerts.
- Inspect the box: If you're buying a Series 9 or Ultra 2 from a third-party seller (like eBay or a local shop), look for the part number. Models ending in LL/A that were shipped after the ban often have the feature disabled.
- Prioritize the screen: Buy the Series 10 for the wide-angle OLED and the thinness. These are the real upgrades. If you're only buying it for "health tracking," you might find more value in a device that hasn't been legally sidelined.
- Wait for the appeal: If you already own a Series 10, keep your software updated. While there's no guarantee, a legal settlement or a successful appeal could theoretically re-enable the sensor via a watchOS update in the future.
The Series 10 remains an incredible piece of engineering. It's just a shame that one of its most sophisticated sensors is currently nothing more than a tiny, expensive paperweight for millions of users.