A comprehensive study of the magnetic transition, magnetocaloric effect, critical behavior, and universal behavior for Mn1-x CoGeSi (x) (x = 0.02, 0.04, 0.06, and 0.08) system is reported. The Curie temperature increases from 270 to 289 K as the Si doping increases, while the maximum magnetic entropy change (|Delta S (M)|) decreases from 3.08 to 2.67 J/kg K (5 T), consistent with the shift of magnetic moment. Various techniques are used to determine the critical exponents and confirm the validity of the obtained critical exponents, revealing long-range interactions in this system. The Landau theory and universal behavior are used to evidence the second-order nature of the transition. Moreover, the new method to estimate the spontaneous magnetization estimated from the magnetic entropy change is verified.