Outside sensor Low

Ideal Outside sensor Fault Code

Also written as OUTSIDESENSOR — same fault.

The Ideal Outside sensor fault code means: your boiler's outdoor temperature sensor is not communicating correctly, which may affect how efficiently the system adjusts your heating based on the weather.. It appears on 2 Ideal models 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: Outside sensor fault (if fitted) detected by diagnostic feature.

What causes the Ideal Outside sensor fault?

This fault occurs when the connection between the boiler and the external temperature sensor is broken or sending incorrect electrical signals. The most common reason is water ingress or corrosion inside the sensor casing located on your outside wall, or damage to the low-voltage wiring connecting it to the boiler.

This issue is often discovered during the first cold snap of autumn when the system attempts to use weather compensation to adjust your heating for the changing season.

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 fault code

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

Source

Ideal Outside sensor 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