☕ Does your coffee machine make a loud buzzing or humming sound when you press the coffee button?
There’s a good chance the noise is coming from one of the machine’s solenoid valves. Although it can sound alarming, it doesn’t necessarily mean the solenoid has completely failed.
A common cause is a small internal piston that has become stuck or restricted by coffee oils, residue or scale. The electromagnetic coil tries to move the piston, but because it cannot open normally, the valve produces that distinctive buzzing sound.
The good news is that, when the problem is caught early, a proper cleaning cycle may be enough to get it moving again. 🧼
What Is Making the Buzzing Sound?
Most automatic and semi-automatic espresso machines contain electrically operated valves called solenoids. These valves control where water and pressure travel inside the machine.
Inside a solenoid is a small moving piston, sometimes called a plunger.
When you start making coffee, an electromagnetic coil activates and moves the piston into position. Under normal conditions, this happens almost instantly.
If the piston becomes sticky or jammed, however, the coil continues trying to move it. Instead of the valve opening normally, you may hear a loud:
BUZZZZZZZZZZ
In simple terms, the buzzing can be the energised solenoid coil trying—and failing—to move the internal piston.
Why Does a Coffee Machine Solenoid Get Stuck?
Two of the most common causes are coffee residue and mineral scale.
☕ Coffee Oils and Residue
Every coffee leaves behind small amounts of oil and residue. Over time, this contamination can accumulate around the group head and throughout the brew circuit.
If enough residue reaches the solenoid valve, its internal piston can become sticky and may no longer move freely.
🪨 Scale and Mineral Deposits
Minerals in the water can gradually build up inside valves, boilers and narrow water passages.
Scale around the solenoid piston can restrict its movement and eventually prevent the valve from opening or closing correctly. This is one reason regular cleaning, suitable water and on-time descaling are so important.
Can Cleaning Fix a Buzzing Solenoid?
Sometimes, yes.
If coffee oils or residue are only beginning to make the piston stick, running a proper group-head cleaning or backflush cycle may dissolve and flush away enough contamination to restore normal operation.
🧼 Start with the correct cleaner: If coffee oils are making the solenoid piston stick, a proper group-head cleaning cycle may help clear the restriction.
👉 Shop 100-pack group-head cleaning tablets — remove coffee oils and help prevent solenoid sticking →
Use a proper espresso-machine cleaning tablet and follow the cleaning instructions supplied by your machine’s manufacturer. A group-head cleaning cycle is different from descaling: cleaning tablets target coffee oils, while descaling products target mineral deposits.
After a thorough cleaning cycle, you may find that the solenoid begins operating normally and the buzzing disappears.
Cleaning tablets will not fix every fault. If the valve is heavily scaled, mechanically damaged or completely seized, the machine may need to be dismantled so the solenoid can be inspected, manually cleaned or replaced.
Don’t Ignore Buzzing That Continues
⚠️ If the buzzing continues after cleaning, avoid repeatedly operating the machine in the hope that it will clear itself.
Other symptoms may include:
- Little or no water coming through the group head
- Loud humming when the coffee button is pressed
- Intermittent water flow
- Normal operation during one coffee but buzzing during the next
- Water or pressure being directed somewhere unexpected
- Repeated clicking or buzzing from inside the machine
- Unusually wet coffee pucks or water behaving oddly in the drip tray
These symptoms can have several causes. A blocked shower screen, pump problem, restricted water path or electrical fault can sometimes produce similar behaviour.
Switch the machine off and unplug it if you notice a burning smell, electrical tripping, leaking near electrical components or an unusually harsh buzzing sound.
Owners of compatible Breville Barista machines can also read our related guide: Breville Barista Express BES870 three-way solenoid faults: symptoms, fixes and replacement.
Prevention: Clean Your Group Head Weekly
🧼 Prevention can make a big difference.
For machines used regularly, we recommend completing a group-head cleaning cycle approximately once a week, or as directed by the manufacturer.
Regular cleaning helps remove coffee oils and residue before they have an opportunity to accumulate throughout the brew circuit and around the solenoid valves.
Think of cleaning tablets as routine preventative maintenance—not something to use only after the machine displays a cleaning warning or develops a fault.
👉 Buy group-head cleaning tablets for weekly preventative cleaning →
A few minutes of cleaning each week can help keep the group head, valves and internal brew circuit cleaner while reducing the likelihood of sticky solenoids and poor water flow.
You can also browse our coffee-machine parts, cleaning products and maintenance items, available through our online shop.
☕ Add a Puck Screen to Help Keep Grounds Away from the Group Head
For Breville 58mm machines, a puck screen sits on top of the tamped coffee and adds a barrier between loose grounds and the shower screen. It helps keep the shower screen cleaner and complements routine cleaning of the brew circuit.
Our 58mm Puck Screen for Breville Dual Boiler & Oracle suits BES900, BES920, BES980, BES990, BES985 and BES995, as well as other compatible 58mm baskets. Add it after tamping and leave enough space above the puck.
A puck screen does not replace cleaning tablets, backflushing or descaling. It cannot guarantee that residue will never reach the solenoid, and it will not fix a valve that is already buzzing, blocked or damaged. If the noise continues after the correct cleaning cycle, have the machine assessed.
👉 Shop the 58mm puck screen — $19.95
Buzzing Still There After Cleaning?
🔧 If you’ve completed the correct cleaning cycle and the machine still makes a loud buzzing noise while brewing, the solenoid may need to be manually cleaned, tested or replaced.
Home Coffee Machine Repairs diagnoses and repairs Breville, DeLonghi, Nespresso and other domestic coffee machines. We can determine whether the problem is being caused by the solenoid, pump, scale buildup or another restriction inside the machine.
📍 Local to Perth?
Perth customers can bring their coffee machine directly to our workshop in Kardinya for assessment and repair.
View our coffee-machine repair service or contact Matt about your machine before bringing it in.
📮 Elsewhere in Australia? You Can Post Your Machine to Us
You don’t need to live in Perth to ask us about repairing your machine.
Customers elsewhere in Australia can contact us about securely posting their coffee machine to our Perth workshop. Tell us the make, model, your location and what the machine is doing before sending it so we can confirm the next step and advise what should be included.
Once the machine arrives, it can be assessed, repaired and properly tested before its return is arranged.
👉 Contact us about posting your coffee machine in for repair
You may also want to check our coffee-machine troubleshooting guides first. Some faults have a straightforward solution; if yours doesn’t, professional diagnosis is the safest next step.
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