What to check, in order
- In freezing weather, check the condensate pipe
It's the plastic pipe that runs from the boiler to a drain outside. Ice in it stops the boiler.
- Thaw it gently
Switch the boiler off at the control panel and turn the electricity off at the wall. Find the frozen part, usually the most exposed part of the pipe outside. Warm it along its length with a hot water bottle, a microwaveable heat pack or warm water poured from a watering can.
- Check the flue outside
From outside, make sure nothing, such as plants, is blocking the flue terminal.
- Reset the boiler
On boilers with a selector switch, turn it to R and hold it there for at least 5 seconds, then let go. If yours has a reset button, press it until the red light goes out. On boilers reset with the temperature control knob, turn it fully anticlockwise, hold it until the red lockout light goes out, then turn it back to your setting.
When to call a Gas Safe engineer
If the pipe wasn't frozen or E28 comes back, call a Gas Safe registered engineer. Baxi's list of causes is a flue sensor fault, an air pressure switch fault, a blocked flue, a blocked condensate or a wiring fault.
Parts people end up buying
Only if the checks above point to a part. Match it to your model number first: it's on a label on the data badge, usually under the boiler or behind the front cover.
- Condensate pipe laggingSearch on Amazon
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Quick answers
What does the Baxi E28 fault code mean?
Baxi lists E28 as a flue temperature sensor fault, and its Platinum user guide adds that it can mean a blocked flue or condensate drain. In freezing weather, Baxi includes it among the codes a frozen condensate pipe can cause.
Can I fix Baxi E28 myself?
Easy (about 30 minutes). Start with: in freezing weather, check the condensate pipe; thaw it gently; check the flue outside. If the pipe wasn't frozen or E28 comes back, call a Gas Safe registered engineer. Baxi's list of causes is a flue sensor fault, an air pressure switch fault, a blocked flue, a blocked condensate or a wiring fault.
Is Baxi E28 worth repairing?
Usually free. In freezing weather it's often a frozen condensate pipe you can thaw yourself. Otherwise it needs an engineer.
Checked against
- Baxi Professional: boiler error codes
- Baxi Platinum Combi 24, 28, 33 and 40 user guide (PDF)
- Baxi: what do error codes E23, E53, E133, E119 or E128 mean
- Baxi: how to thaw a frozen boiler condensate pipe
Last reviewed October 2026. Manufacturers update their pages, and your manual is the final word. Spotted a mistake? Email contact@appliance-error-codes.com.