BoilerFaultCodesYour boiler has been left in a manual testing mode after a recent service or inspection, which is preventing it from running normally.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Check service mode switch is in max position
What causes this fault?
This fault occurs when the boiler is accidentally left in its manual override or 'chimney sweep' mode, which is normally used by engineers to test the system at full power. Because this mode is only meant for short-term testing, the boiler will prevent normal operation to protect the internal components from overheating. It most commonly happens when an engineer forgets to flick the internal service switch back to its normal position after a maintenance visit.
DIY fix possible
Locate the internal control dials on the front of the boilerIdentify the service 'chimney sweep' switch or adjustment dialEnsure any test switches are turned back to the 'off' or 'normal' position rather than 'max'Reset the boiler by pressing the reset button for five seconds
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