Baxi / Main / Potterton · Compact, Duo-tec, Platinum, Assure and EcoBlue platform
E28Flue NTC sensor open- or short-circuit
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
- Do not remove the boiler case or interfere with the flue.
- If the manual identifies a frozen external condensate pipe as a possible cause, follow only the manufacturer's external thawing instructions.
- Otherwise switch the boiler off and arrange a Gas Safe registered engineer.
How an engineer may fix it
Inspect the flue and air path, condensate system, burner, fan or Venturi, sensors and combustion readings; clear, repair, adjust or replace as the appliance instructions require.
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.