Character sums over products of prime polynomials

We study sums of Dirichlet characters over polynomials in ${\mathbb{F}}_q[t]$ with a prescribed number of irreducible factors. Our main results are explicit formulae for these sums in terms of zeros of Dirichlet L-functions. We also exhibit new phenomena concerning Chebyshev-type biases of such sums when the number of irreducible factors is very large.