High Lockout
E17 on Remeha Avanta Plus 35c

Your boiler's computer brain has encountered a communication error or internal failure and cannot safely operate.

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

Internal control unit error

What causes this fault?

This fault occurs when the boiler's main control board suffers an internal electronic failure or loses the ability to communicate with its own sensors. It is often caused by damaged wiring or a degraded circuit board that can no longer process the data needed to run the boiler safely.

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

E1View →E15View →

Related guides you might find useful

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 →

When to replace your boiler

7 signs repair isn't worth it anymore.

Read →