E99 High

ECA E99 Fault Code

The ECA E99 fault code means: your boiler has encountered a deep-seated electronic internal error that has caused it to shut down for safety.. It appears on 3 ECA models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Hardware Faults 4 (lockout) — specific fault in hardware; switch off and on boiler; if persists notify ECA authorised service
Typical repair cost £280-450 (including labour)

DIY fix possible

Locate the power switch or fused spur for the boilerTurn the power off and wait for 30 secondsTurn the power back on and see if the error clears

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ECA models that show the E99 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

ECA E99 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