Why has my coffee machine stopped working properly?

Coffee machines rarely fail electronically. They accumulate scale in the boiler and pipework, and coffee oils in the group head, and both reduce performance gradually enough that people do not notice until it is severe.

What you'll need

• Descaler
• Cleaning tablets or powder
• Brush (optional)
• Replacement seal (optional)

Step by step

1. Descale it, thoroughly and on schedule.Reduced flow, slow heating and lukewarm coffee are the classic scale symptoms. In a hard water area this may be needed every month or two.
2. Backflush or clean the group head.For espresso machines, a cleaning tablet or powder removes coffee oils from the group. Rancid oils there taint every shot.
3. Check and clean the shower screen.Unscrew it and soak it. A blocked screen gives uneven water distribution and channelled, sour shots.
4. Inspect the group seal.A hardened or cracked rubber seal causes leaking around the portafilter and poor pressure. It is an inexpensive part and a simple replacement.
5. Check the water path for blockages.Tank filter, intake pipe, and any inline filter. Machines that pull weakly or not at all often have a blocked intake rather than a failed pump.
6. Check the grind if the symptom is flow rate.Espresso running too fast or too slow is usually the grind, not the machine. Rule that out before dismantling anything.
7. Clean the milk system immediately after every use.Purge the steam wand and wipe it while hot. Milk residue bakes on and blocks the wand, and it is unhygienic.
8. Empty and rinse the water tank regularly.Water left standing grows biofilm and tastes stale. Fresh water daily makes a noticeable difference to the cup.

Tips

• Use filtered water in a hard water area. It dramatically reduces descaling frequency and prolongs the machine's life.
• Note the descaling schedule in a calendar. Machines usually have a warning light, but it is often based on cycles rather than actual water hardness.
• Most home machine faults are consumables — seals, screens, filters. Check parts availability before assuming it needs replacing.

Common mistakes

• Never descaling — Scale builds on the heating element and in the pipework, reducing flow and temperature stability until the machine fails entirely.
• Ignoring a blocked shower screen — It gives uneven water distribution, which causes channelling and sour shots that look like a grind problem.
• Leaving milk in the steam wand — It bakes on inside the wand, blocks it, and is a hygiene problem. Purge and wipe it immediately after every use.

Questions people ask