  A stochastic cellular automaton exhibiting parity conserving class transition
has been investigated in the presence of quenched spatial disorder by large
scale simulations. Numerical evidence has been found that weak disorder causes
irrelevant perturbation for the universal behavior of the transition and the
absorbing phase of this model. This opens up the possibility for experimental
observation of the critical behavior of a nonequilibrium phase transition to
absorbing state. For very strong disorder the model breaks up to blocks with
exponential size distribution and continuously changing critical exponents are
observed. For strong disorder the randomly distributed diffusion walls
introduce another transition within the inactive phase of the model, in which
residual particles survive the extinction. The critical dynamical behavior of
this transition has been explored.
