Why won't my Si114x or Si1132 device respond to Commands?
Answer
The Si1141, Si1142, Si1143, Si1145, Si1146, Si1147, and Si1132 devices have a minimum i2c speed requirement of 90 khz. Writes to the Command register at speeds below this mimimum speed will have unpredictable behavior.
Sensors Knowledge Base
Minimum i2c speed