@calvinx thanks for your informative and really fast reply!!.
I didn't quit understand why you took the "throw out the window" so hard haha.
This is an electronic part that sit few inchs from 300 Celsius so it can go faulty.. And since I didn't see any guide to test the ir probe itself, without duet like with arduino only,i wanted to go with the easy solution, sometimes the time you spent on diagnostic part just not worth it and the smart thing would be to buy a new one, especially when you know it worked in the past in the exact same rig so you know something happened just to him.
In the end after a week of fighting with him and at some point even took him off and map the surface manually i found the problem.
And I only blame Murphy's law! Haha.
In the middle of the ir sensor there is a black capacitor,i guess when i replaced the nozzle to steel one i touched it and bent it by i dunno less then 10 degrees, you can notice it is bent but only from short distance.
So I bent him back with zero force and tweezers and wolla!! It is now only see the right distance that is 2.something mm.
So I suspect that the angle and the fact that the capacitor reflection are high it somehow reflected the ir even from 6mm.
Because the capacitor is well solderded to the sensor so it wasn't a short of any kind.
Bottom line, my fault as usual 
But thanks again for your help!