There are 3 reasons why the measurement signal may be in hold. All 3 reasons result in the same behavior, but they also interact with each other.
Wash-related hold and external hold are connected in parallel. If at least one of them is active, the measurement result is in hold.
Tolerance time is independent of the wash-related hold and external hold, but the tolerance time is reset whenever there is another reason for the measurement hold. For example, if the tolerance time is set to 10 s, and wash hold becomes active after 7 s, the remaining tolerance time resets to 10 s After the wash is over, 10 s of tolerance time still remain.