BoilerFaultCodesGrant PP1 Fault Code
The Grant PP1 fault code means: your boiler has stopped working because it cannot correctly measure the temperature of the water returning to the unit.. It appears on 2 Grant models in our database.
Technical description: Inlet (return) water temperature sensor failure
What causes the Grant PP1 fault?
This fault occurs when the boiler's control board loses communication with the sensor that monitors the temperature of the water coming back from your radiators. The most common reason is that the internal components of the sensor have failed or the electrical connection has become loose or corroded. Because the boiler cannot safely monitor the water temperature, it shuts down to prevent potential overheating.
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 PP1 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Grant PP1 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