H.01-.00 Boiler Fault Code: What It Means on Every Brand

The H.01-.00 fault code appears on 2 boiler brands — Baxi and Remeha — and on all of them it points to the same kind of problem. The details still differ by brand (thresholds, sub-codes, reset procedure), so use the table below to jump to the page for your boiler.

Engineer may be needed 2 brands use this code

Which brand is your boiler?

The brand is printed on the front casing. Tap your brand for the full causes, fixes and repair costs.

Brand	What H.01-.00 means	Severity	DIY?
BBaxi	The H.01 – .00 code appears when your Baxi boiler detects a temporary loss of communication between the gas valve and the PCB (Printed Circuit Board). Full guide →	Engineer may be needed	No
RRemehashown as H.01.00	The H.01.00 code on a Remeha boiler is a blocking fault labelled 'Comm Error', indicating that the boiler's internal electronics have lost communication between key components — typically… Full guide →	Engineer may be needed	No

H.01-.00 brand by brand

Baxi H.01-.00

The H.01 – .00 code appears when your Baxi boiler detects a temporary loss of communication between the gas valve and the PCB (Printed Circuit Board). Because the boiler can no longer confirm that the gas valve is responding correctly, it raises this blocking fault to protect the system. The 'H' prefix means it is a temporary or blocking fault rather than a full lockout — the boiler may recover on its own once conditions improve, but if the code keeps returning you should treat it as a persistent problem requiring professional attention. This code is closely related to E.02.17, which is the permanent version of the same communication fault. If H.01 – .00 escalates to E.02.17, the boiler will lock out completely and a Gas Safe engineer must diagnose the root cause.

Causes, fixes & costs for Baxi H.01-.00 → · All Baxi codes

Remeha H.01.00

The H.01.00 code on a Remeha boiler is a blocking fault labelled 'Comm Error', indicating that the boiler's internal electronics have lost communication between key components — typically between the main PCB and the control panel or display board. Unlike a full lockout (E-prefix codes), a blocking fault (H-prefix) means the boiler has halted as a safety precaution but has not permanently shut down; it may attempt to restart on its own or after a reset. The fault can stem from a loose connector, damaged wiring on the communications bus, a misconfigured parameter, or a failed PCB or control panel. A single reset is always worth trying first — a momentary power glitch can trigger this code — but if the fault returns the boiler needs hands-on attention from a Gas Safe registered engineer.

Causes, fixes & costs for Remeha H.01.00 → · All Remeha codes

Frequently asked questions

Is the H.01-.00 fault code the same on every boiler?

Broadly, yes — on Baxi and Remeha the H.01-.00 code points to the same class of fault, and the recommended response is similar. Model-specific details such as sub-codes and reset procedures still vary, so follow the page for your own brand.

Can I fix a H.01-.00 fault myself?

Not usually. On every brand listed, H.01-.00 points to a fault that needs a suitably registered engineer to diagnose and repair. A single reset to rule out a transient glitch is reasonable; repeated resets are not.

Who should I call about a H.01-.00 fault?

For gas boilers, a Gas Safe registered engineer — it is a legal requirement for any work on the appliance. If you smell gas at any point, leave the property and call the National Gas Emergency line on 0800 111 999.

General guidance only — not a substitute for professional advice, and not certified by a registered engineer. Any work on a gas appliance must be carried out by a Gas Safe registered engineer. If you smell gas, call 0800 111 999.