86 High

Ideal 86 Fault Code

The Ideal 86 fault code means: your boiler is receiving an confusing signal from the pipe that brings water back from your radiators, so it has paused operation to prevent any potential strain on the system.. It appears on 6 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: RETURN TEMPERATURE SENSOR
Typical repair cost £120-200 (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 86 fault code

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

Source

Ideal 86 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 7 July 2026