How much does it cost to fix Main error code 27?

Typical repair cost for the Main 27 fault is £120-250 including labour.

27 High

Main 27 Fault Code

Q: What does the Main 27 fault code mean?

Your boiler is struggling because it either cannot circulate water correctly or there is not enough water pressure inside the system to operate safely.

The Main 27 fault code means: your boiler is struggling because it either cannot circulate water correctly or there is not enough water pressure inside the system to operate safely.. It appears on 2 Main models in our database.

Technical description: Fault on Pump or Low System Pressure

Typical repair cost £120-250 (including labour)

DIY fix possible

Check the system pressure gauge on the front of the boiler; if it is below 1 bar, locate the filling loop.Open the filling loop valves to top up the system until the needle reaches 1.5 bar, then ensure the valves are tightly closed.Restart the boiler to see if the fault clears.

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →

Main models that show the 27 fault code

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

Source

Main 27 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