Vaillant ecoTEC 65kW Fault Codes

System Natural Gas 65 kW 2006-2018 Discontinued

GC Number: 41-044-67

Replaced by: ecoTEC plus 48-64kW

The fault code is already on your display

Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →

All 1 fault code

Code	Severity	Plain English	DIY
S.O	Low	Your boiler is working correctly but is currently in standby because it hasn't received a signal from your thermostat to turn the heating on.	Yes

Status & diagnostic codes

These codes indicate your boiler's operating state or a diagnostic reading — not necessarily a fault. Status codes (S.) mean normal operation; diagnostic codes (D.) are informational readings used by engineers.

Code	Type	Description
S.1	Status	Your boiler is trying to start up but the internal fan is not spinning properly, preventing the heating from firing up.
S.2	Status	Your boiler has sensed that water isn't moving through the unit as quickly as it should be, causing it to stop heating to prevent overheating.
S.3	Status	Your boiler is struggling to light its flame, meaning your heating and hot water will likely stop working soon.
S.4	Status	Your boiler is currently firing up to provide central heating and is functioning as expected.
S.6	Status	Your boiler's fan is staying on for too long or running when it should be finished, preventing the next heating cycle from starting safely.
S.7	Status	Your boiler is struggling to circulate water properly after turning off the heating, which is likely caused by a blockage or a pump issue.
S.8	Status	Your boiler is temporarily pausing heating because it thinks the house is warm enough or to prevent the system from getting too hot too quickly.
S.20	Status	Your boiler has received a request to provide hot water but is currently unable to complete the cycle, often because it is already cooling down or busy with another task.
S.22	Status	Your boiler has detected a problem with the flow of water while trying to heat your taps, which usually means water isn't moving through the system correctly.
S.24	Status	This is a normal status message indicating that your boiler is currently working correctly to heat your hot water.
S.31	Status	Your boiler is currently set to summer mode, which means it is only providing hot water and has intentionally ignored the request for central heating.
S.34	Status	Your boiler has paused because it detects a risk of its internal pipes freezing while trying to heat your home.
S.85	Status	Your boiler is struggling to move enough water through its system, which is slowing down its performance.

Vaillant ecoTEC 65kW is discontinued — time for a new one?

Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.

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