This paper describes integrated numerical modelling applied to JET ITER-like wall H - mode discharges using the COREDIV code, which self-consistently solves 1D radial transport of plasma and impurities in the core region and 2D multi-fluid transport in the SOL. In this paper we focus on sensitivity studies to give insight on the influence of different code input parameters on the simulations results. Simulations show, that for a given power and density value, there is always a limit on the seeding level, above which the self-consistent solution does not exists. This limit seems to be related to the edge density limit and might impose severe consequences on the accessible JET operational domain. Therefore, numerical investigations have been done to check how this limit can be released. It has been found that changes in the edge density, and in particular in the SOL transport can somehow mitigate this effect.