DIAGNOSIS The coffee puck is offering too little resistance. This is almost always due to the grind being too coarse, the dose being too small, or not enough tamping pressure (though the Impress auto-tamps, so that's less likely).
FIX First, adjust your grind. Make it significantly finer—turn the grind dial one or two notches clockwise. Keep your dose consistent (use the reprogrammed auto-dose or a scale). If you're using the Impress's auto-tamp, ensure you're pressing the lever down fully until it clicks and locks. A finer grind will increase resistance and push the pressure needle into the "espresso range."
IF THAT DIDN'T WORK If the grind is already very fine and pressure is still low, you might have a worn or damaged group head seal, which is allowing water to bypass the puck. This is a replaceable part, but requires disassembly.
HEADS UP Don't go insanely fine too quickly, or you'll choke the machine (no flow, max pressure). Adjust incrementally.