Low Warning
LED 1 fast pulse on Ideal Mini S18

Your boiler has detected a minor electronic sensor issue and is running at a lower power level to keep your home warm until it can be serviced.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description

The boiler will continue to operate with a reduced performance in some fault conditions.

What causes this fault?

This fault occurs when one of the internal temperature sensors sends an inconsistent signal to the main control board, suggesting the sensor is starting to fail or has a poor electrical connection. Instead of shutting down completely, the boiler enters a safety mode to prevent overheating while still providing basic heating. The root cause is typically wear and tear on the thermistor component or moisture affecting the wiring harness.

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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