On a coffee machine, limescale buildup is by far the most common source of trouble: a light that won’t turn off, weak flow, a noisy pump, lukewarm coffee. Descaling regularly, using a method suited to your model, prevents most of it before it starts.
Every symptom page below ranks causes by how often they turn out to be the real problem, includes at least one test you can run without buying anything, and tells you plainly when a fix is a quick job versus when it’s time to contact the manufacturer. Coffee machines, single-serve models like Keurig especially, are sealed units with no real parts catalog, so replacement is sometimes the honest answer instead of a repair.
Won’t Turn On
A Keurig that won’t power on at all is rarely a dead machine: a loose cord, a tripped GFCI outlet, or a water reservoir that isn’t seated correctly account for most cases. Full breakdown: Keurig Won’t Turn On or Not Working: 7 Causes Ranked by Likelihood.
Not Brewing
A Keurig that powers on but produces little or no water is usually an air lock in the lines, a reservoir that isn’t seated, or a clogged entrance or exit needle, not a failed pump. Full breakdown: Keurig Not Brewing: 6 Causes Ranked by Likelihood.
Descale Light Won’t Turn Off
If the machine powers on fine but the descale indicator stays lit no matter what you do, the cycle usually wasn’t run to completion or the rinse wasn’t thorough enough. Full breakdown: Keurig Descale Light Won’t Turn Off: 5 Causes Ranked by Likelihood. For the descaling procedure itself, see our how-to-descale guide.
Leaking Water
Water pooling under or around the machine is usually an overfilled reservoir, a blocked valve at its base, or a full drip tray mistaken for a leak, rather than a cracked machine. Full breakdown: Keurig Leaking Water: 6 Causes Ranked by Likelihood.
Preventive Maintenance
Descale every 3 to 6 months, or as soon as the descale light comes on, whichever comes first, since hard water shortens that interval. Use filtered water if your tap water is very hard, to space out descaling sessions. Empty and rinse the water reservoir every few days rather than topping off stale water, and wipe down the exterior and drip tray so grounds and spills don’t attract pests. See our descaling guide for the full procedure.
Repair or Replace?
Most single-serve coffee machines, Keurig included, are sealed units without a real parts catalog: no official replacement fuse, pump, or control board sold to consumers. Cord, outlet, reservoir, and descaling fixes cost nothing and solve the majority of complaints. Once the internal fuse or control board has actually failed, replacement is usually the only realistic option, typically $80 to $200 depending on the model. Machines still under warranty (usually one year) should go back to the manufacturer directly rather than being opened up. For the full cost breakdown, see our coffee maker repair cost guide.
When to Contact Support
Contact the manufacturer if you smell burning, see melted plastic near the cord, or the descale light won’t clear after two complete descale-and-rinse cycles plus a full reset. None of the diagnostics on this site are a substitute for the manufacturer’s own support line once a sealed unit is involved.
Frequently Asked Questions
Can I repair the appliance myself?
Simple checks (filters, seals, settings) are accessible to anyone, appliance unplugged. Electrical work should be left to a professional.
Are the suggested diagnoses guaranteed?
No. These are leads based on the most frequent causes, never certainties.
What if my error code isn’t listed here?
Check your model’s manual: the same code can vary by brand and year.
The information provided here is a diagnostic aid and does not replace the intervention of a qualified professional.