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Coffee machine not working after descaling

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In short

The usual causes are air trapped in the water line, a descaling cycle that did not finish, a water filter refitted dry or without being activated, or loosened scale blocking a valve. Refill the tank with fresh water, prime the pump through the hot water outlet or steam wand, and rerun or complete the rinse stage. Soak and refit the filter properly. If the machine still will not pump or heat, contact the maker.

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Descaling should make a coffee machine work better, so it is frustrating when it stops working straight afterwards. The good news is that the cause is usually simple and temporary. Descaling involves emptying and refilling the water system, removing the filter, and sometimes interrupting the machine mid-cycle. Any of those can leave air in the pump, a warning stuck on screen or a flake of scale where it should not be. Here is how to work through it.

Common causes

SymptomLikely causeFix
Pump runs, no waterAir lock in the linePrime through hot water outlet or wand
Descale light still onCycle unfinished or not resetComplete rinse stage or reset counter
Water tank warningTank or filter not seatedRefit tank; soak and refit filter
Slow or no flowLoose scale in valves or screenRun more rinse water; clean screen
Coffee tastes oddDescaler not fully rinsedRun two extra tank rinses
Error codeInterrupted programmeRestart programme as manual says
Why machines stop after descaling

Step 1: prime the system

Air locks are the most common cause. They happen when the tank is emptied during descaling or the machine runs dry. Priming pushes water back through the pump. On some manual machines, opening the steam valve while the pump runs is the quickest way to draw water through.

  1. 1

    Fill the tank with fresh cold water to the max line and seat it firmly.

  2. 2

    Place a jug under the hot water outlet or steam wand.

  3. 3

    Open hot water or steam and let it run until water flows steadily without spitting.

  4. 4

    On bean-to-cup machines, run a rinse cycle or the hot water drink two or three times.

  5. 5

    Try a coffee. If it flows, run another tank of rinse water to be sure.

Step 2: finish or restart the descale programme

Bean-to-cup machines run a descale programme in stages: descaler, pause, then rinse. If you switch off or remove the tank mid-way, the machine may stay in descale mode or show a warning. Restart the programme from the menu and let it run through the rinse stage. Some machines need you to confirm with a button press before rinsing begins.

If the descale warning stays on, check the manual for how to reset the counter. For model steps, see descaling a De'Longhi Magnifica, descaling a Sage Barista Express or descaling a Gaggia Classic.

Step 3: check the water filter and tank

Most makers say to remove the water filter before descaling. When you refit it, it usually needs soaking or rinsing first, and on many machines you must tell the machine a filter is fitted. A dry filter can trap air and block flow. Soak it as the instructions say, push it firmly into place and activate it in the menu. If you are not using a filter, make sure the filter setting is switched off.

Check that the tank valve at the bottom is not stuck, and that the tank clicks fully home. Our Sage water filter guide shows the fitting steps for Sage machines.

Step 4: loose scale and odd tastes

Heavy scale can break off in flakes during descaling and lodge in a valve, spout or shower screen. Run several more tanks of fresh water through the coffee and hot water outlets. On manual machines, remove and clean the shower screen. If coffee tastes chemical or sour, the descaler has not been rinsed fully; run two more full rinse cycles.

Descaling with vinegar can leave a lingering smell and is not recommended by most makers. Our vinegar explainer explains why.

Note:If the machine trips the electrics, leaks inside the case or will not heat after priming, unplug it and contact the maker or a qualified repairer. Do not open the case.

Preventing it next time

  • Use the maker's descaler and follow the programme without interrupting it.
  • Keep the tank filled during the rinse stage.
  • Descale when prompted rather than letting scale build up.
  • Set the correct water hardness so prompts come at the right time; our water hardness converter helps.

See bean-to-cup machines with guided descaling →

Frequently asked questions

Why is no water coming out after descaling? Usually an air lock. Prime the pump through the hot water outlet or steam wand until water flows steadily.

How long does descaling take? Most programmes take around 20 to 45 minutes including rinsing. Check your manual for your model.

Can descaling damage a machine? Using the right product as directed should not. Overly strong or wrong descalers can harm seals, which is why makers specify their own.

Why is my coffee weak after descaling? The grinder setting has not changed, but the machine may still be rinsing through. Run a couple of coffees and adjust strength if needed.

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