Fix it
Espresso Machine Troubleshooting
Fix sour shots, missing crema, weak steam, and common espresso machine problems with grind, dose, and maintenance fixes.
Most espresso problems are not machine failures; they are grind, dose, or maintenance issues wearing a disguise. Work through these fixes in order, changing one variable at a time, and keep notes on what each shot tasted like. The machine is usually innocent.
Shots taste sour and sharp
Sour means under-extracted. Grind finer in small steps, and check that you are dosing enough coffee for the basket, typically 18 grams for a double. Make sure the machine is fully heated; a cold thermocoil or boiler produces sour shots on the first pull of the day. Fresh beans, roasted within the last month, also extract more evenly than stale ones.
No crema, or thin pale crema
Crema comes from fresh coffee and correct pressure. Beans more than a month off roast lose the CO2 that forms crema, so check the roast date first. Then confirm your grind is fine enough that the shot takes 25 to 30 seconds; a 10-second gusher has no crema because water never properly met the coffee. Pressurized baskets fake crema from stale coffee, which is why beginners sometimes see more crema than they should.
Weak steam or no steam pressure
On single-boiler machines, confirm you switched to steam mode and waited for the boiler to reach steam temperature; steaming too early gives a sad dribble. Purge the wand before steaming to clear condensed water. If steam was strong and faded, the steam tip holes may be clogged with milk residue; soak the tip and clear each hole with a pin.
Shots taste bitter and harsh
Bitter means over-extracted. Grind coarser, shorten the shot, or lower the dose slightly. Check water temperature: a boiler that has been sitting at steam temperature will scorch the next shot, so run a cooling flush through the group before brewing. Dark roasts also read as bitter when ground too fine.
Water leaks around the portafilter during extraction
Leaking at the group head usually means the group gasket is worn or dirty. Remove the portafilter, wipe the gasket seat clean of coffee oils, and inspect the gasket for cracks or flattening; gaskets are cheap wear parts on machines like the Gaggia Classic Pro. Overfilling the basket so the puck presses against the shower screen also forces leaks.
Machine runs but no water flows
Check the water tank is seated correctly; most machines will not pump from a misaligned tank. Then descale: mineral buildup blocks thermocoils and valves, and hard-water households should descale on schedule rather than waiting for symptoms. If the pump runs loud and dry with a full, seated tank, the intake line may be airlocked; a few seconds of running with the steam wand open often clears it.
Questions, answered
How often should I descale?
Every 2 to 3 months with average tap water, more often with hard water. Scale is the most common cause of weak flow and temperature problems, and it is entirely preventable. Use the descaler type your manufacturer recommends.
Why do my shots vary day to day?
Beans age and humidity changes demand grind adjustments; a setting that was perfect last week drifts as the coffee degasses. Grind a touch finer as beans age past two weeks off roast, and keep dose weight consistent with a scale.
When is it actually the machine's fault?
When maintenance is current and technique is consistent but symptoms persist: pump runs with no pressure, boiler never reaches temperature, or leaks from inside the chassis. Those point to failed pumps, thermostats, or seals, and machines like the Gaggia Classic Pro and Rancilio Silvia have documented repair paths.
Should I use filtered water?
Yes. Filtered water with moderate mineral content improves taste and dramatically slows scale buildup. Avoid distilled or zero-mineral water, which tastes flat and can confuse boiler sensors.