BoilerFaultCodesWhat the manual says
Manufacturer manualFlame detector input signal is outside the limits (0 or 5 V). Electronics defective
From this model's manual
Verified against the Vaillant Ecotec Plus 615 installation & service manual, page 43.
What causes this fault?
This fault occurs when the boiler's main control board receives an impossible or conflicting electrical signal from the flame sensing system. The most common reason is an internal electronic failure within the printed circuit board (PCB) itself or a total malfunction of the sensing electrode that monitors the burner.
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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