The LISA Technology Package experiment (LTP) on board the LISA Pathfinder satellite underwent a series of tests late in 2011 where the LTP Diagnostics Subsystem (DS) was tested for the first time in space conditions after integration to the satellite, following a series of characterisation thermal experiments. Such DS will provide in flight key information regarding the thermal and magnetic field stability together with monitoring of charged particles that will be used to ensure that the LTP environment is kept at temperature and magnetic stabilities below 100uK/root(Hz) and 100nT/root(Hz) respectively, in the LTP measuring frequency band from 1mHz to 30mHz. This environment is required to guarantee that the LTP differential acceleration requirement of 3x10^-14 m/s^2/root(Hz) is not affected from such perturbations. In this presentation we will report the main results from the DS during the campaign and the current status of the mission.