ERROR CODE 5 High

Ideal ERROR CODE 5 Fault Code

Also written as ERRORCODE5 — same fault.

The Ideal ERROR CODE 5 fault code means: your boiler has detected a problem with the internal sensor that monitors the temperature of the water for your radiators.. It appears on 2 Ideal 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: CH THERMISTOR FAULT

What causes the Ideal ERROR CODE 5 fault?

This fault occurs when the internal sensor responsible for tracking the temperature of the water leaving the boiler becomes faulty or disconnected. The most common reason is that the sensor has suffered electrical failure over time or the wiring connecting it to the main control board has developed a loose connection, preventing the boiler from safely regulating heat.

Typical repair cost £90-160 (including labour)

Engineer required

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

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Ideal models that show the ERROR CODE 5 fault code

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

Source

Ideal ERROR CODE 5 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