Baxi / Main / Potterton · Compact, Duo-tec, Platinum, Assure and EcoBlue platform
E129Frequent flame loss during calibration ignition
This code applies to Baxi Platinum Compact Combi, Baxi Duo-tec Compact Combi, Baxi Megaflo Compact System, Main Eco Compact Combi & System, Baxi 600 Combi & System, Baxi 800 Combi & System, Baxi Duo-tec Combi, Baxi Assure Combi & System, Baxi Platinum Combi, Potterton Assure Combi & System, Baxi Platinum+ Combi, Baxi Megaflo System, Baxi EcoBlue Combi & System. Fault codes narrow down the likely problem, but they do not replace a model-specific diagnosis.
What you can safely check
- Check whether another gas appliance works and whether a prepayment meter has credit.
- In freezing weather, visually check an accessible external condensate pipe for ice and follow the manufacturer's thawing guidance if applicable.
- Reset once only if the user manual permits it. If the code returns, arrange an engineer.
How an engineer may fix it
Test the gas supply and inlet pressure, ignition and ionisation components, condensate route, flue, gas valve and combustion settings; repair or replace the failed component.
Manufacturer source: Baxi Professional — Boiler Error Codes. Checked 15 August 2026. The appliance manual and an engineer’s on-site diagnosis take precedence. Never remove the boiler case yourself.