B1
FAULT CODE
Worcester Bosch
PCB Internal Fault
High Severity
Engineer Required
The main Printed Circuit Board has detected an internal error it cannot recover from.
Step-by-Step Fix Guide
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Step 1
Turn the boiler off at the mains for 10 minutes then restart
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Step 2 Engineer only
If B1 persists, the PCB will likely need replacing — call a Gas Safe engineer
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.