When the watch is unable to adjust its time in accordance with a calibration signal for some reason, average timekeeping accuracy is within ±15 seconds per month.
GPS signal and time calibration signal reception will not be possible under any of the watch conditions described below.
While battery power is low
While the watch is in the Airplane Mode, Stopwatch Mode, Timer Mode, or Alarm Mode
When power saving is at Level 2 (GPS signal reception also is not possible at Level 1.)
While the crown is pulled out
Timer countdown operation in progress
While the temperature of the watch is less than approximately -10°C (14°F) or greater than approximately 60°C (140°F)
Note that an internal decoding process the watch performs after it receives a signal may cause the time setting to be slightly off (by less than one second).
If the receive operation is successful, the time and day settings will be adjusted automatically in accordance with the Home City (time zone) and summer time settings. Summer time will not be applied correctly in the cases described below.
When the summer time start date and time, end date and time, or other rules are changed by authorities
When position information cannot be acquired correctly
When position information can be acquired, but it is wrong because the watch is located near a time zone boundary, etc.
As of December 2014, China does not observe summer time. If China starts to observe summer time in the future, the time displayed by the watch for China may not be correct.