BoilerFaultCodesBaxi 125 Fault Code
The Baxi 125 fault code means: your boiler has detected that hot water is not flowing around your heating system correctly, which is causing it to shut down to prevent overheating.. It appears on 23 Baxi models in our database.
Technical description: R Circulation Fault (Primary)
What causes the Baxi 125 fault?
This fault occurs when the boiler's internal sensors detect that the water temperature is rising too quickly because it isn't being moved away from the burner. The most common reason is a seized or failing pump, though it can also be caused by an airlock or a blockage in the system preventing the water from flowing. For your safety, the boiler shuts down immediately to prevent the heat exchanger from reaching dangerous temperatures.
This fault is frequently seen at the start of autumn when heating systems are turned back on after months of inactivity, which can cause the internal pump to seize.
DIY fix possible
Check that your system pressure is between 1 and 1.5 bar on the pressure gaugeEnsure all radiator valves and isolation valves under the boiler are fully openBleed your radiators to remove any trapped air pockets
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 125: 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 125 fault code
Click a model for the full fault code list and model-specific repair notes.
- 100/2 HE Plus Repair: £120-£350
- 124 Combi Repair: £150-£350
- 128 Combi Repair: £150-£350
- 615 System 15 Repair: £150-£300
- 618 SYSTEM Repair: £150-£300
- 624 System 24 Repair: £150-£300
- 818 System Repair: £150-350
- 824 SYSTEM Repair: £150-350
- Assure Repair: £150-350
- Duo-tec Combi ErP Repair: £150-350
- Duo-tec Combi GA Repair: £150-£350
- Duo-tec Combi HE A Repair: £150-300
- EcoBlue Repair: £150-£350
- Ecoblue Advance Combi Repair: £150-350
- EcoBlue System Repair: £150-350
- Neta-tec Combi 24 GA
- Neta-tec Combi 28 GA
- Neta-tec Combi 33 GA
- Platinum Combi HE A Repair: £120-250
- PLATINUM COMPACT 25 COMBI Repair: £150-300
- PLATINUM COMPACT 30 COMBI Repair: £150-300
- PLATINUM COMPACT 36 COMBI Repair: £150-300
- Platinum+ 40 Combi Repair: £150-300
Source
Baxi 125 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 31 August 2026