BoilerFaultCodesWorcester Bosch 1-E3 Fault Code
Also written as 1E3 — same fault.
The Worcester Bosch 1-E3 fault code means: your boiler's internal electronic computer chip is either missing, loose, or incompatible with the unit's software.. It appears on 3 Worcester Bosch models in our database.
Technical description: Code plug number: Coding plug number.
What causes the Worcester Bosch 1-E3 fault?
This fault occurs when the boiler's control system cannot communicate with its 'identity chip,' which tells the unit its specific model and power settings. This usually happens if the chip has vibrated loose from its socket on the main circuit board or if the chip itself has suffered an internal electrical failure. In some cases, a power surge may have corrupted the memory or damaged the printed circuit board where the chip is housed.
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-E3 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 1-E3 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