I have an older (3 years) Bosch 125BO that has a standing pilot. After fixing a bad sonnection to the sensor on the upper right (says 120 deg.) that runs from the thermocouple and to the temp sensor, it will light and stay lit, only to go out later in the day. I can relight it and run hot water on and off, just to return later and the pilot is out again. I am puzzled, please help. I don't know what that sensor that says 120 deg. on it is or does, but it was the problem origionally.

thank you in advance.