Outside sensor (if fitted) Low

Ideal Outside sensor (if fitted) Fault Code

Also written as OUTSIDESENSORIFFITTED — same fault.

The Ideal Outside sensor (if fitted) fault code means: your boiler has lost connection with its outdoor thermometer, meaning it might struggle to adjust its temperature correctly for the weather.. It appears on 1 Ideal model in our database.

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 diagnostics will indicate the nature of the fault to assist a speedy and effective repair

What causes the Ideal Outside sensor (if fitted) fault?

This fault occurs when the communication link between your boiler and the external sensor is broken or sending illogical data. The most common reasons are moisture getting into the sensor casing, corroded electrical connections, or the thin wiring being accidentally damaged by garden maintenance or pests.

This fault is more common following periods of heavy rain or snow, which can cause moisture to penetrate the sensor housing and short-circuit the sensitive electronics.

Typical repair cost £90-180 (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 Outside sensor (if fitted) fault code

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

Source

Ideal Outside sensor (if fitted) 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