Junkers boilers: problems and how to solve them

Junkers boilers have common faults just like any other domestic heating equipment, but something that makes these models stand out is that they have their problems fully identified with codes. This way it is easier to know what is going wrong in the equipment, to attend it efficiently and on time.


Junkers is the name of a brand of German origin that is known for offering the public options in water heaters , to enjoy a pleasant bath at any time of the day. However, and considering that it is electronic equipment, it is possible that breakdowns may occur that require the repair of the boilers.

Problems in which the boiler turns off and on constantly or any other type of breakdown in the automatic Junkers heater can be easily identified, thanks to the brand’s code system.

These codes vary for Junkers heaters with problems, as virtually every model could display different indications if the Junkers heater shuts down or the boiler does not light the burner, to name a couple.

Consequently, we have compiled several of the Junkers heater error codes, so that you can recognize them and know what to do in various situations and learn how to fix the EA error on a Junkers boiler, as well as any other.

Junkers Minimaxx Excellence

The Excellence range offers good performance equipment, but problems can occur such as a Junkers heater not lighting burners or perhaps a red light on the boiler.

A7 – Problems with the connections on the temperature sensor.

Solution: Check the status of the wiring and sensor connections inside the equipment, to adjust or replace as required.


A9 – Bad installation of the temperature sensor.

Solution: Check that the installation of the temperature sensor is correct.


C2 – Opening of the pressure switch during use.

Solution: When this happens, you should check the smoke outlet and also do maintenance to the ducts.


E9 – The temperature limiter has been activated.

Solution: Unplug the device from power and wait 10 minutes before using it again. If it persists, contact technical support.


EA – No flame.

Solution: If the problem is “my boiler does not light the flame”, check that the gas valve is set, that there is no air in the pipes and that there is correct pressure.


EC – Problem with ionization.

Solution: Check the status of the connections between the ionization probe and the equipment.


F7 – There is flame, but the equipment is not connected.

Solution: Take a look at the system electrodes, the plate and also the plug.


FA – Flame remains after gas is removed.

Solution: Check that the gas valve is not damaged.

Junkers Cerapur – Cerapur Excellence

The models in this range usually work with a separate thermostat that makes handling and configuration much easier, as well as being very efficient at home.

However, it is possible to find a Junkers heater that does not turn on or that the pressure of the boiler rises with heating, for example. That is why it is so important to recognize what each error code indicates and thus know how to deal with the problem.

A7 – Fault in the water temperature sensor.

Solution: The temperature probe should be checked for proper connection or replaced.


A8 – Cable communication was interrupted.

Solution: Make sure the bonding wire hasn’t slipped out and tighten it if it loosens.


B1 – Keyed connector missing.

Solution: Check that a correct union has been established with the coding connector.


B2/B3 – Data error in the system.

Solution: Faced with this error, we advise you to call a specialist technician.


C6 – Fan failure.

Solution: Check the integrity of the fan, as well as its connections.


CC – Fault in the outside temperature sensor.

Solution: Check that there are no interruptions in the connection between the outdoor temperature sensor and the connection cable.


E2 – Fault in the outlet temperature sensor.

Solution: Check the integrity of the temperature probe and the status of its connection.


F0 – Internal fault of the equipment.

Solution: On the Junkers heater, the F0 error requires a general check of the contacts, connections and wiring.

Junker Cerapur ACU Smart

The Cerapur ACU Smart line offers units that use fuel to run, but natural gas and its breakdowns can be quite common if you don’t make sure your heater is properly maintained.

C1 264 – Fault detected in the fan.

Solution: Check that there are no blockages in the element, as well as that it is connected correctly.


C4 273 – Excessive heater usage.

Solution: Put the equipment out of service for a while, to carry out a general control and review.


E2 350 – Fault in the outlet temperature sensor.

Solution: This part typically requires replacement and requires specialized attention.


EA 227 – There is no flame in the burner.

Solution: On the Junkers heater, the EA error can be caused by several things, including the gas valve. Therefore, it is advisable to check that it is not damaged.


F0 – Internal fault in the equipment.

Solution: Before trying anything else, restart your computer by pressing Reset on the panel. If the problem persists, perform a full service.


C6 215 – Fan overspeed.

Solution: Maintain the gas system, either by cleaning or replacing a part.


C6 216 – Fan too slow.

Solution: Check that the fan cable is in good condition and that there is no dirt or blockage that could affect it.


Now that you know what to do if your Junkers boiler has a red indicator light that flashes and shows an error code on its screen, it will be much easier to enjoy trouble-free operation.

Similarly, many advise resetting the Junkers boiler and guaranteeing its maintenance on time, to prevent any of the errors mentioned in this guide from occurring.

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