BoilerFaultCodesVokera GREEN LED ON every 0.5-secs Fault Code
Also written as GREENLEDONEVERY05SECS — same fault.
The Vokera GREEN LED ON every 0.5-secs fault code means: your boiler is in a temporary standby mode because it has detected a minor issue, such as low water pressure or a momentary sensor error.. It appears on 5 Vokera models in our database.
Technical description: Temporary fault, e.g.: APS fault, low water pressure
What causes the Vokera GREEN LED ON every 0.5-secs fault?
This fault occurs when the boiler's internal computer receives an unexpected reading from a safety sensor, such as the water pressure being too low or the fan not moving air correctly. The boiler enters a temporary standby mode to prevent damage while it waits for the system conditions to return to normal. The most common reason is a simple drop in system pressure that requires the heating loop to be topped up with water.
DIY fix possible
Check the pressure gauge on the front of the boiler; if it is below 1 bar, top it up to 1.5 bar using the filling loop.Ensure the blue mode selector switch is set to the 'ON' or 'DHW' position.Turn the selector dial to 'Reset' for a few seconds and then back to your desired setting.
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Gas Safe Register →Vokera models that show the GREEN LED ON every 0.5-secs fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vokera GREEN LED ON every 0.5-secs fault code information on this page is sourced and cross-checked against the official Vokera service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026