BoilerFaultCodesBaxi 110 Fault Code
The Baxi 110 fault code means: your boiler has switched itself off because it has reached too high a temperature, likely due to trapped air or a blockage stopping water from circulating.. It appears on 21 Baxi models in our database.
Technical description: R Safety Thermostat Operated (pump fault) followed by 20, 28, 40, 160 or 321 indicates possible faulty components.
What causes the Baxi 110 fault?
This fault occurs when the water inside your boiler becomes too hot, causing a safety sensor to trip and shut the system down to prevent damage. The most common reason is that the water cannot move around the system properly, often due to an airlock in the pipework or a pump that has failed. It can also happen if your radiator valves are all closed or if there is a physical blockage restricting the flow.
This fault is frequently seen in autumn when heating systems are turned back on after a long summer break, as pump components can seize up from lack of use.
DIY fix possible
Turn off the boiler and allow it to cool down completely.Use a radiator key to bleed all radiators to remove any trapped air.Check the boiler pressure gauge and top it up to 1.5 bar if it has dropped.Turn the boiler back on and press the 'Reset' button.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Avoid the next call-out bill
A cover plan would handle faults like 110: no call-out fees, no surprise bills.
Affiliate links. We may earn a commission at no extra cost to you.
Baxi models that show the 110 fault code
Click a model for the full fault code list and model-specific repair notes.
- 100/2 HE Plus Repair: £100-280
- 124 Combi Repair: £180-£350
- 200 / 400 Combi Repair: £150-300
- 600 Combi (range) Repair: £120-280
- 624 Combi Repair: £100-280
- 818 System Repair: £100-280
- 825 Combi Repair: £90-250
- Assure Repair: £150-300
- Duo-tec Combi ErP Repair: £120-220
- Duo-tec Combi GA Repair: £90-180
- Duo-tec Combi HE A Repair: £150-£300
- EcoBlue Repair: £150-300
- Ecoblue Advance Combi Repair: £150-300
- EcoBlue Advance Heat Repair: £100-250
- EcoBlue Heat Repair: £100-250
- EcoBlue Plus Combi Repair: £150-300
- EcoBlue System Repair: £180-350
- Suprima 100 Repair: £100-280
- Suprima 30 Repair: £90-250
- Suprima 70 Repair: £120-280
- Suprima 80 Repair: £100-280
Source
Baxi 110 fault code information on this page is sourced and cross-checked against the official Baxi service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026