What is a circulation pump?

Distinct from the drain pump, the circulation (or wash) pump recirculates water through the spray arms during the wash. When its bearings drag it draws high current, whines, and cannot build spray pressure — dishes come out gritty even though the machine appears to run normally. Always clean the filter and check the spray arm jets first, because a clogged filter mimics a dying pump almost exactly and costs nothing to rule out.