308 557 Medium

Ideal 308 557 Fault Code

Also written as 308557 — same fault.

The Ideal 308 557 fault code means: your boiler is likely having trouble reading the temperature setting because the control knob is faulty or incorrectly positioned.. It appears on 1 Ideal model in our database.

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description: Thermostat knob
Typical repair cost £70-130 (including labour)

DIY fix possible

Carefully turn the thermostat knob back and forth several times to clear any dust from the internal sensor.Ensure the knob is firmly pushed onto its spindle and not loose.Set the dial to your desired temperature and check if the boiler fires up.

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Ideal models that show the 308 557 fault code

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

Source

Ideal 308 557 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