Fix it
Coffee Maker Troubleshooting (2026)
Fix common coffee maker problems: weak or bitter coffee, slow brewing, brewer will not start, and descale warnings.
Most coffee maker problems are scale, grind, or cleanliness issues rather than mechanical failures. Work through these fixes before replacing the machine.
Coffee tastes weak or watery
First check your coffee-to-water ratio (roughly 1 to 2 tablespoons per 6 oz), then grind finer: too-coarse grounds under-extract in drip brewers. If the ratio and grind are right, descale the machine; scale buildup lowers brew temperature, which produces weak, sour coffee.
Coffee tastes bitter or burnt
Grind coarser and check that you are not over-extracting with the bold setting plus a fine grind. The most common cause is coffee sitting on the warming plate too long: brew only what you will drink within 90 minutes, and lower the keep-warm setting if your brewer allows it.
Brewing is very slow or stops mid-cycle
Descale immediately: mineral buildup clogs the water lines and is the top cause of slow brewing. Also check that the filter basket is not overfilled and the lid is closed fully, since some brewers pause when the lid sensor is not engaged.
Brewer will not start or the descale light stays on
For will-not-start: check the outlet, the power switch, and that the carafe is seated (many brewers will not run without it). For a persistent descale light: run the full descaling cycle with the manufacturer's recommended solution, not just vinegar, then run two fresh-water cycles; the sensor often needs the complete routine to reset.
Questions, answered
How often should I descale?
Every 1 to 3 months depending on water hardness. Hard-water households should descale monthly; it is the single highest-impact maintenance task.
Can I use vinegar to descale?
It works in a pinch, but manufacturer descaling solutions are formulated to dissolve scale without leaving odors. Run at least two fresh-water cycles after any descaling.