BoilerFaultCodesWorcester Bosch 3.E Fault Code
Also written as 3E — same fault.
The Worcester Bosch 3.E fault code means: your boiler is struggling to provide hot water because it is overheating and shutting down too quickly during its operation cycle.. It appears on 1 Worcester Bosch model in our database.
Technical description: Cycle time (hot water - combi only)
What causes the Worcester Bosch 3.E fault?
This fault occurs when the boiler detects that it is heating up too quickly or reaching high temperatures before it can transfer that heat to your running tap. This is usually caused by a buildup of limescale or debris inside the internal plates, which restricts the flow of water and forces the boiler to shut down to prevent damage. Essentially, the boiler is generating heat but has nowhere for it to go, leading to a constant cycle of starting and stopping.
This issue is often more noticeable in winter when users increase the demand for hot water and the temperature difference between incoming cold water and the desired output is at its highest.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Worcester Bosch models that show the 3.E fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 3.E fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026