A light and sound indicator always warns the user if the
pump is operating with no fluid in it (running empty). This
is combined with the fact that the pump simultaneously
runs at maximum speed until both the pump and pressure
hose are again completely filled with fresh fluid.

If the pressure exceeds 4 bar, e.g. if the nozzle is too
small or a pressure hose is twisted, the pump stops
automatically with both warning indicators (light and
sound) having been activated.

If there is a drop in voltage or any other electrical fault,
the green on light, flashes or goes out.