Blood Oxygen app unavailable on Apple Watch Series 9 GPS

This just worked on my Apple Watch Ultra 2

Found this by Googling Blood O2 app not working and it fixed mine

The Blood Oxygen app is available on Apple Watch Series 6 and later, including Apple Watch SE (2022), Apple Watch Ultra, and Apple Watch Ultra 2. It is not supported on earlier models such as Series 5, Series 4, or the original Apple Watch SE. If you have a compatible model and still cannot use the feature after updating, you may be affected by the bug described below.

How to fix Blood Oxygen not working on watchOS 11.6.1

Zollo’s method uses other health sensors on the Apple Watch to “wake” the Blood Oxygen function:

• Open the Heart Rate app on your Apple Watch.
• Take a manual heart rate reading.
• Open the ECG app.
• Perform a full ECG reading.

After completing these steps, the Blood Oxygen app may reappear as active, allowing you to take measurements normally.

Why this Blood Oxygen fix might work

The exact reason this sequence works is unclear, but it likely forces watchOS to refresh sensor permissions and availability, triggering the Blood Oxygen feature to become accessible again.

I tried this sequence and it did not help. Very frustrating that the update is failing and there is so little information about it anywhere.