BoilerFaultCodesECA 91 Fault Code
The ECA 91 fault code means: your boiler's internal memory chip is overwhelmed or malfunctioning, causing the main control board to lose track of its settings.. It appears on 1 ECA model in our database.
Technical description: Data overwork on EEPROM
DIY fix possible
Locate the main power switch or fused spur for the boilerTurn the power off and wait for at least 60 secondsTurn the power back on and press the Reset button to see if the error clears
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ECA models that show the 91 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
ECA 91 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