All coffee machines on the market, regardless of the brand or the coffee preparation system, have a control card and a built-in microprocessor. These cards act as the “brain” of the machine and vary according to the complexity and functions of the coffee machine, but they are necessary for all of them.
The control cards analyse the machine’s state at any given moment and communicate it to the user via LCD screens or lights on its buttons. Those coffee machines with displays inform more effectively than those that encode the information through coloured lights, but in all of them, the mission is the same; to inform the user of the machine’s current status.
Many Keurig coffee machines have an LCD, which is very good at conveying information. However, some models, such as the K-series (K-Compact, K-Classic, K-55, etc.), do not have a display, and interpreting what the lights mean is not always easy.
Green power button light
Once you have plugged in the coffee machine, it will turn on if you press the power button, and the machine will start to heat the water. This process can take up to 4 minutes and will finish when you stop hearing the sound of the boiler.
Red power button light
Some Keurig models have a red light on the power button, which will flash to indicate that water is heating up in the kettle. If, after a few minutes, this light is still flashing and you cannot make coffee, the machine is in “error mode” and will not let you do anything until the fault is fixed.
You should first unplug it from the mains and plug it back in after a few minutes to see if the error disappears. If this has not worked, do a visual inspection of the machine to look for the problem, and if everything is OK, you should take it to a service centre or disassemble it to inspect the inside yourself.
All three brew buttons are flashing
Once the Keurig has been switched on, and the machine has heated the water, the brew buttons will flash when you open and close the capsule holder. This means that the machine is ready to brew coffee.
When you press one of the buttons, it will turn on steady, and the other two will turn off. After 60 seconds, all buttons are disabled, and you have to open and close the capsule holder to make them operational again.
If all three buttons remain flashing after pressing one of them and the machine does not brew coffee, there is a fault in the machine. You can try to reset it by following these steps:
- Unplug the machine from the mains and plug it in again to ensure no light comes on.
- Switch on the machine by pressing and holding the auto-off button + the “medium cup” and “large cup” buttons until all the lights go out.
- Press the power button, and everything should be fine again.
Check our Keurig troubleshooting guide.
All lights flashing at the same time
This is a rare problem in well maintained Keurig coffee machines, but sometimes when there is a blockage in the water circuit, the machine warns us of the problem in this way. It usually appears suddenly when after brewing a cup of coffee, the machine recognises too much pressure in the circuit and prevents us from brewing more cups.
In some models, we will see a combination of lights: “add water” + “heating” + “small cup”, but the meaning is the same. This is an obstruction or the presence of air which prevents the water from circulating. In extreme cases, the pump may be damaged.
To solve this problem, you should try to carry out an emergency descaling; however, if there is no way to get the coffee maker to dispense water, it is too late for this solution.
You can try cleaning the injector needle with a paper clip or a cleaning capsule, but if this is not enough, you should disassemble the brewer and clean all valves and pipes manually. Most probably, a non-return valve located at the injector inlet is blocked.
Descaling mode lights
One of the most important modes that Keurig capsule coffee machines have is the descaling mode. But before we talk about this mode, we must differentiate between when the coffee machine asks us to descale and when it is in descaling mode.
Once we have brewed more than 250 cups of coffee, the Keurig coffee machine will warn us that it is time to descale and flash the light on the “descale” button. If we want to enter descaling mode, we must first switch off the machine, then press and hold the 8oz and 12oz buttons until the descaling light is steady.
Once the descaling light is fixed, we have entered the descaling mode. If the process is done properly, this light will turn off (Download the user manual of your coffee machine here). If it does not turn off, press the 8oz and 10oz buttons for 3 seconds to reset it.
Note: Some models, such as the K-35, do not have a descaling mode but should still be descaled every 3-6 months.
The water fill light is flashing
This light indicates that the water level in the tank is low, but sometimes it will flash even when the tank is full. This can happen for several reasons:
- The water tank may be incorrectly positioned, or the outlet valve may be clogged. Check that the tank is not suffering from these problems.
- If your water tank has a magnet, the magnet may be stuck in the lowest position so that the machine receives a low water signal. Try to release the magnet to solve the problem.
- On other occasions, when there is no magnet or if there is one and it is in its highest position, the flow meter of the coffee machine may be stuck, and the machine recognises that there is no water. In this case, you must disassemble the machine and clean the flow meter.