BoilerFaultCodesWarmhaus E84 Fault Code
The Warmhaus E84 fault code means: your boiler is slowing down its performance because it has detected that the gas pressure coming into the unit is too low to run at full power.. It appears on 1 Warmhaus model in our database.
Technical description: Capacity reduction for detected low gas inlet pressure – check the CO2 calibration values.
What causes the Warmhaus E84 fault?
This fault occurs when the boiler detects that the gas supply pressure is insufficient to maintain the high heat output it is trying to achieve. It is often caused by a bottleneck in the pipework or a gas valve that isn't opening fully, forcing the system to reduce its power to prevent the flame from failing entirely. In some cases, it can also be triggered if the gas meter's regulator is faulty or if the boiler's internal sensors are miscalibrated.
This issue is most frequent during the coldest months when high demand across the local gas network and your own heating system can cause a noticeable drop in inlet pressure.
DIY fix possible
Check that your gas emergency control valve (next to your meter) is fully openIf you have a pre-payment meter, check that you have sufficient creditCheck if other gas appliances, like a hob, are working correctly to rule out a grid supply issue
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Gas Safe Register →Warmhaus models that show the E84 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Warmhaus E84 fault code information on this page is sourced and cross-checked against the official Warmhaus service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026