Vaillant fault diagnostics

Vaillant ecoTEC plus 610 — F.028

The Vaillant ecoTEC plus 610 displaying fault code F.028 indicates an ignition failure, meaning the boiler failed to ignite or detect a flame during startup. This leads to the boiler locking out as a safety measure. Common causes include issues with the gas supply, a blocked or frozen condensate pipe, a faulty ignition system (electrode, lead, transformer), or a defective gas valve or PCB. The clicking sound before lockout is consistent with the boiler attempting ignition. The normal pressure reading suggests the issue isn't related to low system pressure.

Published 22nd June 2026

Vaillant ecoTEC plus 610 — F.040

The Vaillant ecoTEC plus 610 displaying fault code F.040 indicates that the air ratio is too low, often due to a fault in the flue gas route, recirculation, or a blockage. It can also be caused by a blocked air intake pipe or condensate in the combustion chamber due to a blocked condensate discharge. The symptoms of the fan kicking in, ignition sequence attempting, but locking out before ignition, align with this fault code, suggesting an issue preventing proper combustion. Given the intermittent nature and occurrence when firing from cold, it points towards a component that might be struggling to perform correctly under initial demand. The gas tightness check and clear flue terminal/condensate trap are good initial steps, but further investigation into the air/flue system and ignition components is necessary.

Published 2nd June 2026