BoilerFaultCodesGrant DHW pump Fault Code
Also written as DHWPUMP — same fault.
The Grant DHW pump fault code means: your boiler is struggling to manage the temperature of its internal hot water store, meaning you likely have no hot water available.. It appears on 3 Grant models in our database.
Technical description: If flashing this indicates either a store thermistor or PCB fault
What causes the Grant DHW pump fault?
This fault occurs when the boiler's internal computer loses communication with the sensor that monitors the temperature of your stored hot water. The most common reason is that the sensor has developed an electrical fault or the wiring has vibrated loose, preventing the boiler from knowing when to safely heat the water. In rarer cases, the main control board itself may be failing to process the signals it receives.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Grant models that show the DHW pump fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Grant DHW pump 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 27 April 2026