Low
YELLOW LED ON every 0.5-secs on Pro ProCombi 100HE

Your boiler is currently running in a special test mode used by engineers to check combustion levels, which means it is not in its normal operating state.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

CO function active

From this model's manual
Verified against the Pro Procombi 100he installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Locate the selector switch on the front control panel.Ensure the dial is pointed to 'S' (Standby) or 'Run' and not the 'Analysis' or 'Chimney Sweep' position.Turn the boiler off at the fused spur switch, wait 30 seconds, and turn it back on to reset the electronics.

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