BoilerFaultCodesThe 6 most common faults
01
F37 High DIY-safe
Your boiler has stopped working because the water pressure inside your heating system has dropped too low to operate safely.
What to try first
Locate the external filling loop, which is usually a small metal or braided hose located under the boiler.Open the small valve(s) on the loop to allow mains water to enter the system until the pressure gauge on the front of the boiler reads between 1.0 and 1.5 bar.Close the valve(s) tightly and check that the error code has cleared.
02
A01 High Engineer
Your boiler is failing to light the flame, which means it cannot produce any hot water or heating.
Full guide for A0103
A05 High Engineer
Your boiler is unable to safely vent exhaust gases because the internal fan that pushes air through the system has stopped working correctly.
Full guide for A0504
A06 High Engineer
Your boiler is failing to light the internal burner, so it has safely shut itself down to prevent a gas build-up.
Full guide for A0605
F34 High Engineer
Your boiler is temporarily shutting down because it is not receiving enough electricity from your home's power supply.
Full guide for F3406
F41 High Engineer
Your boiler has detected that water is heating up too quickly compared to the sensors' expectations, causing it to shut down to prevent damage.
Full guide for F41on the Ferroli Bluehelix Tech RRT 34C
Pressure relief valveExpansion vesselPressure sensorIgnition electrodeGas valveIgnition lead
Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.
Call a Gas Safe engineer if…
- You can smell gas or see signs of a leak
- The Ferroli shows an Emergency or High severity code
- The boiler keeps locking out after repeated resets
- You've tried the DIY checks and the fault hasn't cleared
- There's visible water leaking from the boiler
- The flame is yellow or orange instead of blue
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