Chris, are you submerging the probe in water when you clean it? Also, are you letting it sit outside, when not in use? If the probe end gets water in it, it will fail. If the plug end gets moisture in it, it will read weird. Not saying that's what's going on, just asking the questions. It's amazing how many of these probes are sent back as "defective," and there's actually nothing wrong with them. Sometimes, they just need to dry out.