BoilerFaultCodesWarmhaus E43 Fault Code
The Warmhaus E43 fault code means: your boiler has lost its connection to your room thermostat, meaning it cannot receive instructions on when to turn the heating on.. It appears on 1 Warmhaus model in our database.
Technical description: Room thermostat communication error – disconnection or communication loss in room thermostat.
What causes the Warmhaus E43 fault?
This fault occurs when the boiler's control board can no longer 'talk' to your room thermostat, usually due to a dropped signal or a hardware failure. The most common reason is simply that the thermostat batteries have run out, but it can also be caused by a faulty wireless receiver or loose wiring between the boiler and its controls.
This fault is frequently reported during the first cold spell of autumn when homeowners try to turn their heating back on after months of inactivity, only to find the thermostat batteries have drained.
DIY fix possible
Check if your wireless thermostat needs new batteries.Ensure the thermostat is within range of the boiler and there are no new obstructions.Check that the thermostat's receiver unit is powered on and plugged in correctly.
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Gas Safe Register →Warmhaus models that show the E43 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Warmhaus E43 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