BoilerFaultCodesECA 424 Fault Code
The ECA 424 fault code means: your boiler has detected an impossibly cold temperature reading on its internal return pipe, which is usually caused by a frozen pipe or a faulty sensor.. It appears on 1 ECA model in our database.
Technical description: Boiler return temperature is not at the desired level (<0 ° C)
DIY fix possible
Check if any external condensate pipes are frozen and thaw them with warm (not boiling) water.Ensure the property's heating is turned up and check if the boiler is located in an unheated area like a garage.Reset the boiler to see if the error was a temporary glitch.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Avoid the next call-out bill
A cover plan would handle faults like 424: no call-out fees, no surprise bills.
Affiliate links. We may earn a commission at no extra cost to you.
ECA models that show the 424 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
ECA 424 fault code information on this page is sourced and cross-checked against the official ECA service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026