E28 on a Potterton boiler means: flue sensor fault, or blocked flue/condensate pipe. There is a problem with the flue (the pipe that carries waste gases out of your home) or the condensate drain, so the boiler has shut down for safety.
Potterton is part of the Baxi group and many models share Baxi's codes.
This code applies to Potterton boilers that use Baxi-group electronics. Codes can mean different things on different models, so check the display against your boiler's user manual.
What you can safely check
- From the ground, check the flue terminal outside isn't blocked by a bird's nest, leaves, plants or anything stored against it.
- In freezing weather, check the condensate pipe for ice. Thaw it with warm (not boiling) water or a hot water bottle.
- Press reset once, following the instructions in your user manual.
When to call an engineer
If the code returns, or you can see damage to the flue, switch the boiler off and call a Gas Safe engineer. Flue problems can let combustion gases into your home, so don't keep running it. A working carbon monoxide alarm near the boiler is a must.
Never remove the boiler casing yourself — everything behind it must be handled by a Gas Safe registered engineer. If you smell gas, open windows, turn the gas off at the meter, and call the National Gas Emergency number on 0800 111 999.
Repair it, or replace it?
If your boiler is over 10 years old, compare a repair against a new combi before you pay for parts.
Applies to: Potterton boilers that use Baxi-group electronics
Meaning checked against: BOXT — Baxi boiler fault and error codes
Last reviewed November 2026. Always follow your boiler's own user manual.