Low Warning
F16 on Intergas Rapid 32

Your boiler has lost its connection to the outside temperature sensor, meaning it cannot automatically adjust its performance based on the weather.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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 open circuit

What causes this fault?

This fault occurs when the electrical path between the boiler's control board and the external sensor is broken. The most common reasons are a loose connection at the terminal block, damaged external wiring caused by weathering, or a complete failure of the sensor’s internal components.

Engineer required

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

Find a Gas Safe engineer
Search the official register →

Related fault codes

F15View →

Related guides you might find useful

Yellow or orange flame — CO safety

Safety-critical — turn off, read this.

Read →

Is boiler cover worth it?

Break-even maths on monthly cover.

Read →

When to replace your boiler

7 signs repair isn't worth it anymore.

Read →