BoilerFaultCodesPotterton No Switched Live Fault Code
Also written as NOSWITCHEDLIVE — same fault.
The Potterton No Switched Live fault code means: your boiler is not receiving the electrical signal from your thermostat or programmer telling it to turn on.. It appears on 2 Potterton models in our database.
Technical description: Failure in the electrical supply to the boiler; check fuses and 230V mains input.
What causes the Potterton No Switched Live fault?
This fault occurs when the boiler is receiving main power but isn't getting the specific 230V command to actually start heating. The most common reason is a failure in an external component like a broken room thermostat, a blown fuse in the wiring center, or a motorized valve that is stuck and failing to trigger the microswitch. Essentially, the boiler is 'waiting' for a signal that never arrives because of a break in the electrical chain outside the unit itself.
This issue is frequently seen during the first cold snap of autumn when heating systems are turned on for the first time after being idle all summer, often revealing a seized zone valve or a thermostat with dead batteries.
DIY fix possible
Ensure your wall thermostat is turned up higher than the current room temperatureCheck that your programmer or heating timer is set to 'ON' or 'AUTO'Check your home's consumer unit (fuse box) to see if any switches have trippedReplace the batteries in your room thermostat if it has a digital display
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Gas Safe Register →Potterton models that show the No Switched Live fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton No Switched Live fault code information on this page is sourced and cross-checked against the official Potterton service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026