I think Kutta is right to suggest that we use the term bias for "a pattern of errors". What is confusing is that we also tend to refer by that term to the underlying process which produces the pattern, and that such a process is beneficial or detrimental depending on what we use it for.

The "Heuristics and Biases" party line is to use "heuristic" to refer to the underlying mechanism. For example, "the representativeness heuristic can lead to neglect of base-rate."