when it's disconnected it show´s 999,9 in serial Monitor. At the moment i only testing it over serial output
are you sure the probe is K-type?
Yes, I am sure. Have another BBQ thermometer. This is called "Wlan Thermometer" http://wlanthermo.com/On this thermometer I use 4 Ikea Fantast probes and 2 TYP-K termoelements on an AD595 signal converter. And so they work without problems.
Great , clean and beautiful make .well done.