What does the Johnson Starley F40 fault code mean?

Your boiler has detected that the water pressure in the central heating system is too low or too high for it to operate safely.

How much does it cost to fix Johnson Starley error code F40?

Typical repair cost for the Johnson Starley F40 fault is £0-160 including labour.

Check the pressure gauge on the front of the boiler or under the casing; it should be between 1.0 and 1.5 bar.

Central heating water pressure fault

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Six most common causes of dropping pressure.

Step-by-step using the filling loop.

7 signs repair isn't worth it anymore.