Baxi · 400 Combi 2.1
H.01.21 boiler fault code
400 Combi 2.1
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What H.01.21 means
Flow temperature increase during hot water operation too fast.
Gas Safe engineer: Note the code shown on the display. Do not open, adjust or repeatedly reset the boiler. Contact a Gas Safe registered engineer.
A boiler fault code alone is not a gas or carbon-monoxide emergency. If you smell gas, a CO alarm sounds, or someone has possible carbon-monoxide symptoms, leave and call 0800 111 999 from outside.
Renting? Report it to your landlord or housing provider first. They are responsible for gas safety and boiler repairs, and the repair should not cost you.
Safe check
Note the code shown on the display. Do not open, adjust or repeatedly reset the boiler. Contact a Gas Safe registered engineer.
When to contact an engineer
Note the code shown on the display. Do not open, adjust or repeatedly reset the boiler. Contact a Gas Safe registered engineer.
Source and provenance
- Baxi 400 Combi 2.1 Installation & Service Manual 7875578-02 · §11.2 Error codes: short list, printed p. 49; temporary faults, printed p. 51
installation and service instructions
7875578-02