What the manual says
Manufacturer manualR Safety Thermostat Operated (pump fault) followed by 20, 28, 40, 160 or 321 indicates possible faulty components.
From this model's manual
Verified against the Baxi Ecoblue Advance Heat installation & service manual, page 64.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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