Molecular dynamics (MD) simulations give us a molecularly detailed view of biological processes. To reach relevant length-and timescales, the number of degrees of freedom can be reduced by coarse-graining (CG). As one of the most successful approaches, the Martini force field on average maps four non-hydrogen atoms into a single bead. With the Martini force field, integration time steps of up to about ∆t = 30 fs can be used, compared to the 2 fs typical in all-atom simulations. CG force fields make it possible to study phase separation in lipid bilayers as possible models for the lipid rafts implicated in a myriad of cellular processes. However, we recently observed unphysical temperature gradients across the liquid-ordered (L o ) and liquid-disordered (L d ) phase boundaries in Martini 2 simulations of phase separating ternary lipid mixtures. We traced these gradients to an insufficient convergence of the highly coupled bond-length constraints in the Martini 2 cholesterol model, with cholesterol being a major component of phase separating lipid membranes. Insufficient constraint convergence also affects other observables at typical time steps, such as the diffusion coefficient or the contact fraction, which describes the degree of the phase separation in the system. Slow convergence of the linear constraint solver (LINCS) is expected for any system with strongly coupled constraints. In Martini 2, this includes sterols such as cholesterol and ergosterol. In atomistic simulations, the issue arises, e.g., for angle-constrained butane or pentane, where LINCS fails entirely, or cholesterol with all bonds constrained. Thus, an easy-to-use tool to estimate the required LINCS settings for proper convergence and a strategy to ameliorate bond length constraint issues would be valuable.