How much does it cost to fix Main error code E385?

Typical repair cost for the Main E385 fault is £80-150 including labour.

E385 High

Main E385 Fault Code

Q: What does the Main E385 fault code mean?

Your boiler has detected that the water pressure inside your heating system is too low to operate safely.

The Main E385 fault code means: your boiler has detected that the water pressure inside your heating system is too low to operate safely.. It appears on 1 Main model in our database.

Technical description: System water pressure fault

Typical repair cost £80-150 (including labour)

DIY fix possible

Locate the filling loop (usually a silver braided hose with one or two valves underneath the boiler).Slowly open the valve(s) to allow water to enter the system while watching the pressure gauge on the front of the boiler.Stop filling once the needle reaches the green zone, typically between 1.0 and 1.5 bar, then ensure the valves are fully closed.

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Main models that show the E385 fault code

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

Insul 7 Repair: £80-150

Source

Main E385 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