  The Pixel Detector is the innermost part of the CMS Tracker. It therefore has
to prevail in the harshest environment in terms of particle fluence and
radiation. There are several mechanisms that may decrease the efficiency of the
detector. These are mainly caused by data acquisition (DAQ) problems and/or
Single Event Upsets (SEU). Any remaining efficiency loss is referred to as the
dynamic inefficiency. It is caused by various mechanisms inside the Readout
Chip (ROC) and depends strongly on the data occupancy. In the 2012 data, at
high values of instantaneous luminosity the inefficiency reached 2\% (in the
region closest to the interaction point) which is not negligible. In the 2015
run higher instantaneous luminosity is expected, which will result in lower
efficiencies; therefore this effect needs to be understood and simulated. A
data-driven method has been developed to simulate dynamic inefficiency, which
has been shown to successfully simulate the effects.
