Replacement Series 7 Watch and iOS 18.6.1 watchOS 11.6.1 Blood Oxygen OK again.

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Level 7

21,373 points

Replacement Series 7 Watch and iOS 18.6.1 watchOS 11.6.1 Blood Oxygen OK again.

My wife’s original series 7 Watch O2 app was working. A few months ago it was replaced under warranty (battery) and the O2 function was disabled on the replacement. After installing iOS 18.6.1 and watchOS 11.6.1 the replacement series 7 Blood Oxygen feature is working again.

So this update reenables the feature on earlier models as well as the 9 10 and Ultra 2. If you had your Watch replaced and the replacement disabled the feature then try updating. O2 was reenabled on my wife’s replacement series 7.

Apple Watch Series 7

Posted on Aug 15, 2025 06:22 AM

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Answer 1

Ingo2711

Level 9

77,853 points

Aug 15, 2025 06:31 AM in response to lkrupp

Apple also issued a news update regarding this feature:

…

Apple will introduce a redesigned Blood Oxygen feature for some Apple Watch Series 9, Series 10, and Apple Watch Ultra 2 users through an iPhone and Apple Watch software update coming later today.

Users with these models in the U.S. who currently do not have the Blood Oxygen feature will have access to the redesigned Blood Oxygen feature by updating their paired iPhone to iOS 18.6.1 and their Apple Watch to watchOS 11.6.1. Following this update, sensor data from the Blood Oxygen app on Apple Watch will be measured and calculated on the paired iPhone, and results can be viewed in the Respiratory section of the Health app. This update was enabled by a recent U.S. Customs ruling.

There will be no impact to Apple Watch units previously purchased that include the original Blood Oxygen feature, nor to Apple Watch units purchased outside of the U.S.

…

copied from: An update on Blood Oxygen for Apple Watch in the U.S. - Apple

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Answer 2

GeeZ06

Level 4

3,168 points

Aug 15, 2025 06:36 AM in response to lkrupp

Hello Ikrupp,

Thanks for the update info. I have the Ultra2 watch that I got before Apple disabled Blood Oxygen feature. The update states the, "Measurements are calculated on the iPhone and viewed in the health app". So does that mean that the iWatch sends data in the background to the iPhone for calculation to be viewed in Health app and NO Blood Oxygen data is shown on the iWatch anymore? Just wondering if I really want to do this update. Thanks!

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Answer 3

KiltedTim

Level 10

221,004 points

Aug 18, 2025 05:46 PM in response to GeeZ06

GeeZ06 wrote:

Hello Ikrupp,

Thanks for the update info. I have the Ultra2 watch that I got before Apple disabled Blood Oxygen feature.

I don't see how that's possible since that model was released after that functionality was disabled.

does that mean that the iWatch sends data in the background to the iPhone for calculation to be viewed in Health app and NO Blood Oxygen data is shown on the iWatch anymore?

That's correct

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