Verified boiler fault code
Potterton E129 Fault Code (Assure Combi & System)
Safety error for frequent loss of flame with maximum correction during ignition calibration.
Safety disclaimer
Fault code summary
- Manufacturer
- Potterton
- Fault code
- E129
- Fault type
- Flame failure, Ignition, Safety lockout
- Severity
- lockout
- Reset
- Not specified
- Applicable models
- Potterton Assure Combi, Potterton Assure System
Quick answer
Safety error for frequent loss of flame with maximum correction during ignition calibration.
What does this fault code mean?
Safety error for frequent loss of flame with maximum correction during ignition calibration.
Common causes
- Frequent flame loss with maximum correction during ignition calibration.
Symptoms
- The boiler displays E129 and may lock out.
What can the homeowner safely check?
- Note the code and contact a qualified engineer if it repeats.
Boiler reset information
Reset information was not provided in the verified manufacturer source. Do not repeatedly reset an unresolved fault.
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 ignition, flame detection, gas supply and calibration by qualified personnel.
Applicable boiler models
Related fault codes
- E09 — Assure Combi & System
Gas valve connection fault.
Read fault code - E10 — Assure Combi & System
External probe fault.
Read fault code - E109 — Assure Combi & System
Precirculation alarm.
Read fault code - E110 — Assure Combi & System
The boiler maximum temperature was exceeded, or the safety thermostat sensor tripped.
Read fault code - E118 — Assure Combi & System
Water pressure is low, below 0.5 bar.
Read fault code - E12 — Assure Combi & System
Differential water-flow switch fault; the switch is still open.
Read fault code - E125 — Assure Combi & System
Water circulation fault.
Read fault code - E128 — Assure Combi & System
Safety error for frequent loss of flame.
Read fault code
Manufacturer documentation
Boiler Error Codes | BaxiPotterton Assure Combi & System — E129: Safety error for frequent loss of flame with max correction during ignition during Calibration Function.
Last verified
2026-09-12
Frequently asked questions
What does Potterton E129 mean?
Safety error for frequent loss of flame with maximum correction during ignition calibration.