All you need instant read thermometer for $14.99

[Mark_E]

Easy way to check it is to put it in a pot of boiling water. It should read 212. or within a degree of that. A cup of ice water should show 32. +-

...unless you're in Denver

 

[Bob Bailey]

Used my ThermoPro TP19HW yesterday and, while cleaning the probe pulled it out of the unit. Fed the wire/sensor back into the probe and pushed it into the unit. Checked against a known accurate thermometer and the readings agreed. It's likely just fine but going to get a backup just in case.
Just ordered a TP623W. Appears to be a newer model with all the same features as the TP19H. Walmart has them for $14.99 after a $5 discount. Will report on it after a few uses.

Well, the TP623W seems to be a little faster than the TP19HW but isn't magnetic. Picked up a magnetic base hook so it now resides on the side of the fridge with a couple of others. Did a side-by-side test in a 160F cup of water and the difference was .2 degrees F. Looks like the TP19 is OK, at least for now.