Junkers Eurline: what each combination of lights (red and green LEDs) means

boiler Junkers Eurhas stopped working and the red LED is lit along with one of the green ones. The Euronline doesn't have a display, so it doesn't show codes like EA or E9: it indicates the fault with a combination of lights. The problem is that this table is only found in the technical manual, and almost no one explains it well.

Here you have all the LED combinations for the Eurline, what each one means, what to check and which boiler code with display it corresponds to, so you can use our detailed guides.

Junkers Eurline fault light table

Information based on the Junkers professional troubleshooting manual for the EurZW…-1. Some combinations (pressure switch and fan) only apply to sealed versions, such as the ZS/ZW 23-1 AE.

The most common Eurbreakdowns, explained

Red + 3rd green: does not detect flame

This is the most common problem. The boiler sparks, but the electrode doesn't detect a flame. First, the obvious: is gas getting through? Check the gas valve and, if you have a gas stove, make sure it's working. If you see the flame appear and then go out after a few seconds, the gas is getting through fine, and the problem is with the detection: a dirty electrode, a loose or grounded electrode, or a damaged wire. We explain this in detail in the EA error Junkers, which is exactly the same fault.

Red + 2nd green: overtemperature

The limiter has tripped because the water has overheated. The Euroline manual Eurthree possible causes: the limiter, a seized pump , and air in the system. Before replacing anything, check the pressure gauge, open the radiators, and bleed the system, including using the boiler's own bleed valve. More details can be found in the E9 error.

Red + 2nd and 5th green: poor gas evacuation

The flue gases aren't venting properly. In sealed models, the manual points to dirty pressure switch ports, a fan that isn't rotating, and the pressure switch itself. In naturally draft models, it points to the AGÜ probe (the draft control device). This is a safety issue: if it happens again, have it checked by an installer. More information is available in the pressure switch.

Red + 3rd and 5th, or 4th and 5th: NTC probes

One of the two temperature sensors is open or shorted: either the primary (heating) sensor or the hot water sensor. Before buying a new sensor, check the connector and cable: they will give the same signal. We explain how to test this in the NTC sensor.

Red + 5° green: slight overheating

The primary NTC sensor detects that the temperature is rising too high, but without triggering the limiter. The manual recommends checking the plate heat exchanger and verifying the NTC sensor. In hard water areas, a limescale buildup in the heat exchanger is the typical cause, especially if the hot water temperature fluctuates.

How to reassemble the Euronline

The Eurhas a reset button on the control panel. Once the problem has been resolved, press it and the boiler will attempt to restart. If the fault reappears after one or two resets, do not persist: the problem remains.

Spare parts for the Junkers Euronline

• Eurline ZW 23 and Neckar electronic module (87083002120)
• Pump for Euroline, Ceraclass Midi ZW 24 and Neckar NW 24 (8738725176)
• Water filter for Eurline and Neckar (87005070740)
• Draft control device / flue gas probe ZW 23 and ZW 24 (87044012060)
• ZW 20 and ZW 23 fan (87072040010)
• Electrodes and spark plug for ZW boilers (87181070500)
• NTC probe for ZW boilers (87004000140)
• Controls for Eurline ZW 23 and ZW 24 (87020002730)

Always check the reference number on your rating plate. All parts are available in spare parts Junkers , and the rest of the codes can be found in the error code table Junkers.

Frequently Asked Questions

Where are the LEDs on the Eurline?

On the light strip of the control panel, next to the reset button and the heating and hot water temperature controls.

Does a red LED always indicate a fault?

Yes: it indicates that the boiler has locked out. The green lights that are lit at the same time indicate the problem.

I have the red and the third green light, but I see a flame. How is that possible?

This is a typical case of a dirty or incorrectly positioned detection electrode: the flame is present, but the boiler cannot detect it. We explain this in the EA error.

Is it worth repairing a Euronline?

It depends on the fault. Electrodes, probes, filters, or the pump are reasonable repairs. If the electronic module fails in an older boiler, it's advisable to get a quote and assess the cost.