BoilerFaultCodesPotterton E78 Fault Code
The Potterton E78 fault code means: your boiler's internal sensor is struggling to accurately read the water pressure, which prevents the system from operating safely.. It appears on 1 Potterton model in our database.
Technical description: Water pressure sensor fault
What causes the Potterton E78 fault?
This fault occurs when the boiler's internal electronic sensor can no longer accurately monitor the water pressure inside the system. The most common reason is that the sensor has suffered an electrical failure or has become blocked by debris and sludge build-up, preventing it from sending a reliable signal to the main control board.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Potterton models that show the E78 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton E78 fault code information on this page is sourced and cross-checked against the official Potterton service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026