High
Case sensor on Potterton Envoy 30

Your boiler has detected a communication failure with a internal safety sensor, causing it to shut down to prevent unsafe operation.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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

Sensor failed open or closed circuit Replace sensor

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Find a Gas Safe engineer
Search the official register →

Related fault codes

E01View →E02View →E03View →

Related guides you might find useful

Boiler keeps losing pressure

Six most common causes of dropping pressure.

Read →

Boiler keeps cutting out

Lockout fault with a reset-needed pattern.

Read →

Yellow or orange flame — CO safety

Safety-critical — turn off, read this.

Read →