Sensor change on Tuesday this week. My last one made it 17 days before giving some really funky readings. It was still somewhataccurate, but not close enough. Strangely, I had that one placed on the left side of my stomach. The new one is on the right side and has been so much more accurate over the following 2 days. Whereas the left side sensor was always off by at least 10 points, the right side one has been spot on for the most part. So I wonder why my right side likes the G4 sensors that much better..... They always did say 'show 'em your good side!'