BoilerFaultCodesWhat the manual says
Manufacturer manualMaximum flow temperature value reached
Shared across the 800 System 2 range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
DIY fix possible
Check that all your radiators are switched on and their valves are fully open to allow water to circulate freely.Verify that your system pressure is correct, typically between 1 and 1.5 bar.Restart or reset the boiler using its control panel once the system has cooled down.
Find a Gas Safe engineer
Search the official register →
Boiler cover options
Avoid the next call-out bill
A cover plan would handle faults like H.01 .14: no call-out fees, no surprise bills.
Approved partner
Get a quote →
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Affiliate links. We may earn a commission at no extra cost to you.
Related fault codes
All 75 fault codes on the 800 System 2
Seeing a different code? Every code this model can display, in one place.
254A.00.34A.02.06A.02.18A.02.36A.02.37A.02.45A.02.46A.02.48A.02.49A.02.54A.02.55A.02.76E.00 .04E.00 .05E.00 .06E.00 .07E.00 .16E.00 .17E.00.20E.00.21E.01.04E.01.12E.01.17E.01.20E.02.13E.02.15E.02.17E.02.35E.02.47E.04.00E.04.01E.04.02E.04.03E.04.07E.04.08E.04.09E.04.10E.04.11E.04.12E.04.13E.04.14E.04.15E.04.17E.04.18E.04.19E.04.20E.04.21E.04.23E.04.24E.04.54H.00.42H.01 .00H.01 .05H.01 .08H.01 .18H.01 .21H.02 .00H.02 .02H.02 .03H.02 .04H.02 .05H.02 .07H.02 .09H.02 .10H.02 .12H.02 .38H.02 .70H.03 .00H.03 .01H.03 .02H.03 .05H.03 .17H.03 .54