BoilerFaultCodesWhat the manual says
Manufacturer manualIgnition transformer not connected. Ignition transformer plug not plugged in or has come loose, multiple plug on the PCB not plugged in correctly, interruption in cable harness, electronics defective
From this model's manual
Verified against the Vaillant/Vaillant Vaillantpro Ecofit Sustain Open Vent Installation And Servicing installation & service manual.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register →
Boiler cover options
Avoid the next call-out bill
A cover plan would handle faults like F.87: no call-out fees, no surprise bills.
Approved partner
Get a quote →
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Affiliate links. We may earn a commission at no extra cost to you.
All 36 fault codes on the ecoFIT sustain 415
Seeing a different code? Every code this model can display, in one place.