BoilerFaultCodesTechnical description
Condensate pump or return signal from accessory module heating: Condensate pump faulty or return signal from the exhaust gas flap has responded
What causes this fault?
This fault occurs when the boiler's safety system detects that the pump responsible for removing waste water is broken or a specific safety flap is stuck. If the condensate water cannot be pumped away, it builds up inside the unit, forcing the boiler to shut down to prevent internal flooding or hazardous gases from escaping. It is essentially a safety 'cut-off' triggered by an issue with an add-on component or accessory module.
This fault is more common during freezing winter temperatures, as external pipes can freeze and cause water to back up, putting extra strain on the pump until it fails.
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.