BoilerFaultCodesKeston E33 Fault Code
The Keston E33 fault code means: your boiler is having trouble measuring the temperature of your hot water because of a faulty internal sensor or a wiring issue.. It appears on 9 Keston models in our database.
Technical description: Domestic hot water (DHW) sensor short circuit – check connections to DHW sensor are in place
What causes the Keston E33 fault?
This fault occurs when the boiler's internal computer receives an incorrect electrical signal from the sensor that monitors your hot water temperature. The most common reason is that the sensor has suffered a physical failure or an electrical short, preventing the boiler from knowing how hot the water is. It can also be caused by loose or damaged wiring between the sensor and 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 →Keston models that show the E33 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Keston E33 fault code information on this page is sourced and cross-checked against the official Keston service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026