BoilerFaultCodesAlpha 0E33 Fault Code
The Alpha 0E33 fault code means: your boiler is struggling to detect the temperature of the water being heated for your taps, which means it has safely shut down to prevent overheating.. It appears on 3 Alpha models in our database.
Technical description: DHW sensor out of range. DHW sensor measures a temperature outside normal working range.
What causes the Alpha 0E33 fault?
This fault occurs when the electrical voltage entering the boiler drops below the minimum level required for its electronic components to function correctly. The most common reason is an instability in your home's mains power supply or a loose connection within the boiler's internal wiring that is restricting the flow of electricity. In some cases, the boiler's main control board may be incorrectly detecting a drop in power due to a failing internal sensor.
This issue can be more frequent during periods of extreme weather or high local energy demand, which can cause temporary fluctuations or 'brownouts' in the national grid supply.
DIY fix possible
Check if other appliances in your home are struggling or if there is a local power cutEnsure the boiler's electrical fused spur switch is fully turned onReset the boiler by turning the selector switch to the 'R' position for 5 seconds
Find a Gas Safe engineer
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Gas Safe Register →Alpha models that show the 0E33 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Alpha 0E33 fault code information on this page is sourced and cross-checked against the official Alpha service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026