What the manual says
Manufacturer manualFlash 4 times per second: CH or DHW Sensor fault or out of position, Air pressure switch fault or condense in tubes, Fan fail or stiff, Blocked flue, Faulty harness, Board fault.
From this model's manual
Verified against the Worcester Bosch/Worcester Bosch Junior 28i installation & service manual.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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All 27 fault codes on the 24i / 28i Junior
Seeing a different code? Every code this model can display, in one place.