Accuracy problem
 

Hello everyone ! I have a quite strange problem with solving of two equations:

initial condition for U is uniform (0 0 0) for E uniform 215250, for p i made a step-like distribution with funkySetFields :

Solution domain is one-dimensional with 10000 cells. The problem is that second equation gives that E changes throughout all solution domain with a small fluctuations about e-12, and after each time step this errors accumulates.
Here 1st 100 values of E :

I use Gauss linear scheme for div(pU) term. I've tried various linear solvers with difference tolerance values, but it doesn't help.