How much does it cost to fix Main error code 23?

Typical repair cost for the Main 23 fault is £120-250 including labour.

23 High

Main 23 Fault Code

Q: What does the Main 23 fault code mean?

Your boiler is struggling to push water around the system, likely because the water pressure has dropped too low or the pump is stuck.

The Main 23 fault code means: your boiler is struggling to push water around the system, likely because the water pressure has dropped too low or the pump is stuck.. It appears on 1 Main model in our database.

Technical description: Fault on Pump or Low System Pressure

Typical repair cost £120-250 (including labour)

DIY fix possible

Check the pressure gauge on the front of the boiler; if it is below 1 bar, find the filling loop underneath the boiler.Open the filling loop valves to let water in until the needle reaches 1.5 bar, then close the valves tightly.Reset the boiler using the reset button on the control panel.

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Main models that show the 23 fault code

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

System 18 HE Repair: £120-250

Source

Main 23 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