How much does it cost to fix Main error code E50?

Typical repair cost for the Main E50 fault is £120-220 including labour.

E50 High

Main E50 Fault Code

Q: What does the Main E50 fault code mean?

Your boiler is struggling to accurately measure the temperature of the water being heated for your taps, so it has stopped providing hot water to ensure your safety.

The Main E50 fault code means: your boiler is struggling to accurately measure the temperature of the water being heated for your taps, so it has stopped providing hot water to ensure your safety.. It appears on 4 Main models in our database.

Technical description: Hot Water NTC Fault

Typical repair cost £120-220 (including labour)

Engineer required

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

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Main models that show the E50 fault code

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

Eco 24 HE Repair: £120-220
Ecoinstaller 2 Repair: £120-200
Insul 7 Repair: £150-300
System 18 HE Repair: £120-£200

Source

Main E50 fault code information on this page is sourced and cross-checked against the official Main service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026