In a previous work, an innovative and patented method was presented, that is based on a new virus surrogate. This surrogate is an enzyme-labelled MS2 phage that is directly detectable and quantifiable by amperometry thanks to its induced enzymatic activity. In this work, this method was used to characterize the dynamics of virus removal in micromodules as a function of the membrane defect size and the transmembrane pressure (TMP). Experiments were performed at lab scale with an integer module and with modules made with the same fibres with calibrated holes (50, 100, 150 mu m) made in one of the module fibres with the laser method. Results showed first that the new method allowed diagnosing a 50 mu m hole on the fibre of a micromodule. It was also demonstrated that, whatever the applied TMP, removal performances are all the more better that the defect size is smaller. Moreover, whatever the hole size, a TMP step rise from 1 to 1.5 bar during tracer filtration led to no significant change in the observed removal but improved the intrinsic removal performances.