I asked this back in October but didn't get any responses. I am hoping that now with more people using the Navigator, someone knows if the sensors are accurate after the expiration date. We have been using each sensor 14 days. We put in a new one every other Saturday. Avoiding the calibration issues on school days, and my dd's dislike of the insertion, was the motivation for the 14 day schedule and it has worked very well for us. Right now we have 2 boxes of senors that will expire at the end of February. They will actually last us 6 months if we keep going as we have. I hate to increase our expense and poke her more often if the senors will continue to be accurate. Thanks for your help.