Purchased from Amazon 12/10/17. After 1 month noticed unusually high outdoor reading in mornings. (+30 degrease from expected) Normal readings in the evening. Last week I started troubleshooting. Brought outdoor sensor indoor next to receiver. Changed batteries with new Energizer Alkaline and checked for corrosion. Outdoor readings were consistently 10 degrees higher than indoor and even higher during mornings. I tried different frequency settings. Originally set to A. I could not even get communication with setting B or C doing complete reset in between each setting. Oddly the receiver will show communication with setting on A even when the transmitter has no batteries installed. I guess something is broken.