D1 218
FAULT CODE
Worcester Bosch
Flow/Return Temp Difference Too High
Medium Severity
Engineer Required
Poor circulation — the temperature gap between flow and return is abnormally large.
Step-by-Step Fix Guide
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Step 1
Check system pressure and bleed radiators
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Step 2 Engineer only
A Gas Safe engineer should check the pump and system for blockages
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.