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error Ideal
Error Code F5 L5
Return thermistor fault — the return water temperature sensor is malfunctioning.
? What Causes This
Issues with the temperature sensors or wiring problems.
✓ How to Fix It
- Restart the boiler system.
- Contact Ideal (warranty period) or Gas Safe Registered Engineer if issues remain.
Source: page 9 of the official manual
From the manual
This error code appears in:
Ideal Boilers I 24