BoilerFaultCodesIdeal LED2 flashing, LED3 on Fault Code
Also written as LED2FLASHINGLED3ON — same fault.
The Ideal LED2 flashing, LED3 on fault code means: your boiler has detected a sensor problem that is preventing it from providing hot water correctly.. It appears on 6 Ideal models in our database.
Technical description: Faulty DHW thermistor or wiring
What causes the Ideal LED2 flashing, LED3 on fault?
This fault occurs when the sensor responsible for measuring the temperature of your hot water fails to provide a consistent reading to the boiler's control board. The most common reason is that the internal components of the sensor have degraded over time, though it can also be triggered by a loose or damaged connection in the electrical wiring. As a safety precaution, the boiler stops heating water to prevent it from becoming dangerously hot or staying stone cold.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Ideal models that show the LED2 flashing, LED3 on fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal LED2 flashing, LED3 on fault code information on this page is sourced and cross-checked against the official Ideal service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026