BoilerFaultCodesWhat the manual says
Manufacturer manualPower supply <170 V
From this model's manual
Verified against the Vaillant Ecomax Pro 28e installation & service manual, page 26.
What causes this fault?
This fault occurs when the electrical voltage entering the boiler drops below a safe threshold, meaning there is not enough power for the internal components to function. Typically, this is caused by a problem with your home's main electricity supply or a failing electronic control board within the boiler itself. In some cases, it can also be triggered by a loose or damaged power cable that is preventing a steady flow of electricity.
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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