H2o Low

Grant H2o Fault Code

Also written as H2O — same fault.

The Grant H2o fault code means: your boiler is operating normally and is simply displaying the current temperature of the water inside the system.. It appears on 1 Grant model in our database.

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.

Technical description: Normal control panel display showing water temperature

DIY fix possible

No action is required as this is a standard status notificationConsult your user manual to confirm other status displays

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →
Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like H2o: no call-out fees, no surprise bills.

Approved partner
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

Grant models that show the H2o fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Grant H2o fault code information on this page is sourced and cross-checked against the official Grant service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026