Low
Orange LED on on Sime Ecomfort HE Combi

Your boiler is currently sitting in sleep mode and is ready to work as soon as you turn on a tap or your heating clicks on.

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

Stand-by / off — normal stand-by condition

From this model's manual
Verified against the P3 Sime Murelle He System 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

Check your room thermostat is turned up high enough to demand heatEnsure your heating programmer or timer is set to an 'On' periodTurn on a hot water tap to see if the light changes to green

Find a Gas Safe engineer
Search the official register →
Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like Orange LED on: no call-out fees, no surprise bills.

Approved partner
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

Related fault codes

Green LED onView →Red LED onView →

Related guides you might find useful

Is boiler cover worth it?

Break-even maths on monthly cover.

Read →

When to replace your boiler

7 signs repair isn't worth it anymore.

Read →

New boiler cost 2026

Realistic UK prices for a swap.

Read →