BoilerFaultCodesWorcester Bosch 1.E Fault Code
Also written as 1E — same fault.
The Worcester Bosch 1.E fault code means: your boiler's internal pump is detecting a communication error or is set to the wrong operating mode, meaning it cannot circulate water properly.. It appears on 1 Worcester Bosch model in our database.
Technical description: Pump switch mode
What causes the Worcester Bosch 1.E fault?
This fault occurs when the boiler's control board loses touch with the internal pump or notices it is running in the wrong setting. The most common reason is an electronic communication failure between the pump and the main computer, often caused by a loose connection or a failing pump motor. Without this connection, the boiler cannot safely move hot water around your system, so it shuts down to prevent 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 →Worcester Bosch models that show the 1.E fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 1.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