Verified boiler fault code
Main Heating E110 Fault Code (Eco Elite System)
Safety thermostat operated.
Safety disclaimer
Fault code summary
- Manufacturer
- Main Heating
- Fault code
- E110
- Fault type
- Overheating, Safety lockout
- Severity
- lockout
- Reset
- The manual says turning the selector fully anticlockwise to Reset and holding it for 5 seconds can relight the boiler when E110 is displayed.
- Applicable models
- Main Eco Elite 24 System ErP, Main Eco Elite 28 System ErP
Quick answer
Safety thermostat operated.
What does this fault code mean?
Safety thermostat operated.
Common causes
- Safety thermostat operated.
Symptoms
- The facia displays E110 and the boiler may stop.
What can the homeowner safely check?
- Record the displayed code; do not remove the boiler casing.
Boiler reset information
The manual says turning the selector fully anticlockwise to Reset and holding it for 5 seconds can relight the boiler when E110 is displayed.
When should I call an engineer?
Contact a suitably qualified heating engineer when the fault persists, the boiler locks out, or the manufacturer instructions do not resolve it. For gas appliance work in the UK, use a Gas Safe registered engineer.
Engineer diagnosis
- Investigate primary-water temperature, circulation and the safety thermostat.
Applicable boiler models
Related fault codes
- E119 — Eco Elite System
Water-pressure switch not operated; the manual states this is shown below 0.5 bar primary-water pressure.
Read fault code - E125 — Eco Elite System
Circulation fault in the primary circuit.
Read fault code - E131 — Eco Elite System
Interruption of power supply while in fault mode.
Read fault code - E133 — Eco Elite System
Interruption of gas supply or flame failure.
Read fault code - E160 — Eco Elite System
Fan or fan-wiring fault.
Read fault code - E20 — Eco Elite System
Central-heating NTC fault.
Read fault code - E28 — Eco Elite System
Incorrect PCB fitted.
Read fault code - E50 — Eco Elite System
Hot-water NTC fault.
Read fault code
Manufacturer documentation
Main Eco Elite System Installation & Service ManualE110 shows overheat of the primary water; turning the selector to Reset for a minimum of 5 seconds can relight the boiler.
Last verified
2026-09-12
Frequently asked questions
What does Main Heating E110 mean?
Safety thermostat operated.
Can I reset a Main Heating E110 fault?
The manual says turning the selector fully anticlockwise to Reset and holding it for 5 seconds can relight the boiler when E110 is displayed.