BoilerFaultCodesVokera Green LED On, Yellow LED On Fault Code
Also written as GREENLEDONYELLOWLEDON — same fault.
The Vokera Green LED On, Yellow LED On fault code means: your boiler has lost water pressure and needs to be topped up to function correctly again.. It appears on 1 Vokera model in our database.
Technical description: Low pressure (Requires 'topping-up')
What causes the Vokera Green LED On, Yellow LED On fault?
This fault occurs when the water pressure inside your heating system drops below the minimum level required for the boiler to fire up safely. The most common reason is a tiny leak from a radiator valve or joint, though pressure also naturally drops if you have recently bled your radiators to remove air bubbles.
This issue is more frequent in autumn when homeowners turn their heating back on for the first time or bleed their radiators to prepare for winter.
DIY fix possible
Locate the filling loop (a flexible metal hose) underneath the boiler that connects two pipes.Open the valves at both ends of the filling loop to allow water to enter the system.Watch the pressure gauge on the front of the boiler until it reaches the green zone (typically between 1.0 and 1.5 bar).Close both valves tightly and remove the filling loop if required by your specific model.
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Gas Safe Register →Vokera models that show the Green LED On, Yellow LED On fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vokera Green LED On, Yellow LED On 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