Apple Watch Series 11 SpO2 measurements suddenly fail everytime

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Level 1

116 points

Apple Watch Series 11 SpO2 measurements suddenly fail everytime

Apple Watch Series 11 SpO2 measurements suddenly fail immediately after starting manual measurement. Last successful measurement was taken on 31/10/2025.

Steps taken:

-restarted both iPhone and Watch

-cleaned back of Watch.

-switched Watch to opposite hand

None of the steps above worked.

Measurements work fine with older Series 8 Watch without problems. Switching watch band from older Watch to newer did not correct issue. The watch has been in use one month. Running iOS 26.01 and watchOS 26.02

Apple Watch Series 11, watchOS 26

Posted on Nov 2, 2025 11:06 AM

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Answer 1

Top-ranking reply

Ingo2711

Level 9

78,735 points

Nov 2, 2025 11:33 PM in response to tomis

Unpairing and setting the watch up as a new device, without using the latest backup would be the way to rule out a software issue.

Unpair and erase your Apple Watch - Apple Support

If this does not help, you should get the watch diagnosed, which the Apple Support can do online:

Contact Apple Support - Apple Support

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