D1 200
FAULT CODE
Worcester Bosch
Heating System Circulation Fault
Medium Severity
Engineer Required
The boiler is detecting poor water circulation in the heating system. The temperature difference between flow and return is too high.
Step-by-Step Fix Guide
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Step 1
Check the system pressure on the gauge — it should be between 1.0 and 1.5 bar
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Step 2
If pressure is low, repressurise via the filling loop
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Step 3 Engineer only
If pressure is fine, there may be a blockage, airlock or pump fault — 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.