The Baxi H.01.00 code means a temporary communication failure between the gas valve and boiler PCB. It describes an interrupted control signal inside the appliance. Because both parts are safety-critical, this is not a homeowner repair.
What does Baxi code H.01.00 mean?
Baxi’s current error-code table defines H.01.00 as a “Temporary communication failure between gas valve and boiler PCB.” The PCB is the boiler’s main electronic control board. The gas valve regulates gas entering the burner under the boiler’s control.
The word “temporary” describes the status recorded by the controls. It does not mean the problem should be ignored, and it does not prove that either the gas valve or PCB needs replacing. The same display can arise from different underlying conditions, and the code alone cannot identify a failed component.
Which Baxi boilers can show H.01.00?
Baxi currently places H.01.00 in the error-code group for these ranges:
- Baxi 200 Combi 2
- Baxi 400 Combi 2
- Baxi 600 Combi 2
- Baxi 800 Combi 2
- Baxi Assure 500 Combi 2
- Baxi 600 System 2
- Baxi 800 System 2
- Baxi Assure 500 System 2
Check the exact product name on the outside of the boiler or in its user guide. Similar-looking Baxi boilers can use different code sets, so the full model matters.
How is H.01.00 different from E.02.17?
Baxi describes H.01.00 as a temporary communication failure between the gas valve and boiler PCB. In the same model group, E.02.17 is listed as a permanent communication failure between those parts. Do not use the distinction to decide which component to replace or to keep operating the appliance. Record the exact code shown and give it to the repair engineer.
What might you notice?
The boiler may pause, fail to provide heating or hot water, or show the code alongside another message. Behaviour can vary by model and by the circumstances in which the communication was interrupted. The display is useful evidence, but it is not a complete explanation of the cause.
What can you safely check?
Keep your checks outside the boiler:
- Write down H.01.00 exactly, including the dots and zeros.
- Confirm the full boiler model from the casing label or paperwork.
- Note whether heating, hot water or both have stopped.
- Record any other code displayed before or after H.01.00.
- Note whether there was a recent power cut, electrical work or boiler service.
- Check that ordinary external controls are calling for heat, without removing any covers.
Do not remove the boiler casing, touch the gas valve, inspect plugs or connectors, test wiring or voltage, work on the PCB, or make combustion adjustments. These are tasks for a suitably qualified engineer.
Should you reset a Baxi H.01.00 code?
Reset methods vary between Baxi models, so follow only the user guide for your exact boiler. If that guide permits a homeowner reset for the situation, make one attempt. Do not keep resetting the appliance if H.01.00 returns. Repeated resets do not repair a communication problem and may make the sequence harder to assess.
When should you arrange a repair?
Arrange a professional repair if H.01.00 remains on the display, returns after the single permitted reset, or leaves you without reliable heating or hot water. Share the exact model, code, timing and any other messages with the engineer.
The engineer can assess the appliance safely and determine why communication was interrupted. The required work cannot be established from H.01.00 alone, so avoid buying parts before the boiler has been checked.
Gas and carbon-monoxide safety
If you smell gas, suspect a gas leak, or a carbon-monoxide alarm sounds, do not reset or use the boiler. Turn off the gas at the meter if it is safe to do so, open doors and windows, leave the property, and call the National Gas Emergency Service on 0800 111 999 from a safe place. If anyone feels unwell, seek urgent medical help.
Gas-appliance work must be completed by an appropriately qualified Gas Safe registered engineer. For more homeowner-safe information, visit our boiler help guides.
Need help with Baxi H.01.00?
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Quick answers about Baxi H.01.00
What does Baxi H.01.00 mean?
It means a temporary communication failure between the gas valve and boiler PCB.
Does temporary mean the boiler is safe to ignore?
No. Temporary describes the control status, not the importance of the fault. If the code stays or returns, arrange professional help.
Is H.01.00 definitely a faulty gas valve?
No. The code describes failed communication and does not identify which part, connection or condition is responsible.
Can I check the gas valve or PCB myself?
No. Do not remove the casing or touch gas, electrical or combustion components. Use a suitably qualified Gas Safe registered engineer.
Can I keep resetting a Baxi H.01.00 code?
No. Follow the exact user guide and, only if it allows, try one reset. A code that returns needs a repair.