B7 257
FAULT CODE
Worcester Bosch
Internal Communication Error
High Severity
Engineer Required
There is an internal communication error between boiler components, typically involving the printed circuit board (PCB).
Step-by-Step Fix Guide
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Step 1
Try switching the boiler off at the spur and back on after 30 seconds
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Step 2
If the fault persists, the PCB or internal wiring may be faulty
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Step 3 Engineer only
A Gas Safe engineer will need to diagnose and potentially replace the PCB
Gas Safe Reminder
Work on gas appliances must be carried out by a Gas Safe registered engineer. The steps above cover safe checks a homeowner can perform - any internal component replacement requires a qualified professional. If in doubt, always call an engineer.