Low
H.01 .21 on Baxi 800 System 2

Your boiler has temporarily paused because the water temperature inside is rising too quickly, and it will try to restart automatically in 10 minutes.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

Flow temperature increase in domestic water mode too quick. Temporary stoppage of 10 minutes

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.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

H.01View →E119View →E133View →

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 .14H.01 .18H.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

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