Vaillant EcoMax Pro 18/28E Fault Codes

Combi Natural Gas 18-28 kW 2001-2006 Discontinued

GC Number: 47-044-21

Replaced by: ecoTEC plus 831

The fault code is already on your display

Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →

Most common fault codes

Code	Severity	Plain English	DIY
F.1	High	Your boiler has failed to ignite and is not producing heat, which is usually due to an interrupted gas supply or a problem with the internal spark system.	Yes
F.4	High	Your boiler is failing to light the flame properly, which means it cannot heat your radiators or water.	Yes
F.5	High	Your boiler has got too hot and has automatically shut down for safety to prevent damage.	Yes
F.6	High	Your boiler has stopped working because a sensor that measures the temperature of the water leaving the unit has stopped sending a reliable signal.	Engineer
F.17	High	Your boiler has detected that the electrical wiring is connected incorrectly or there is a problem with the mains power supply.	Engineer
F.24	High	Your boiler has stopped working because the water isn't circulating properly, likely due to a pump issue or trapped air in the system.	Engineer

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