  We conducted a detailed long-term spectral and temporal study of flat
spectrum radio quasar 4C +01.02, by using the multi-wavelength observations
from Fermi-LAT, Swift-XRT, and Swift-UVOT. The $2$-day bin $\gamma$-ray
lightcurve in the 2014-2017 active state displays $14$ peak structures with a
maximum integral flux $(\rm E > 100 \ MeV)$ of $\rm (2.5 \pm 0.2) \times
10^{-6}\ ph\ cm^{-2}\ s^{-1}$ at MJD 57579.1, which is approximately $61$ times
higher than the base flux of $\rm (4.1 \pm 0.3) \times 10^{-8}\ ph\ cm^{-2}\
s^{-1}$, calculated by averaging the flux points when the source was in
quiescent state. The shortest $\gamma$-ray variability of $0.66 \pm 0.08$ days
is observed for the source. The correlation study between $\gamma$-ray spectral
index and flux suggests that the source deviates from the usual trend of harder
when brighter feature shown by blazars. To understand the likely physical
scenario responsible for the flux variation, we performed a detailed broadband
spectral analysis of the source by selecting different flux states from the
multi-wavelength lightcurve. A single zone leptonic model was able to reproduce
the broadband spectral energy distribution (SED) of each state. The parameters
of the model in each flux state are determined using a $\chi^2$ fit. We
observed that the synchrotron, synchrotron-self-Compton (SSC), and
External-Compton (EC) processes produce the broadband SED under varied flux
states. The adjoining contribution of the seed photons from the broad-line
region (BLR) and the IR torus for the EC process are required to provide
adequate fits to the GeV spectrum in all the chosen states.
