What to check, in order
- In cold weather, thaw the condensate pipe
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.
- Power on and restart
Turn the power back on at the wall and restart the boiler. Repeat the thawing until it works again.
- Reset the lockout
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 it locks out again, call a Gas Safe registered engineer. Baxi says frequent lockouts mean there's a 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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Checked against
- Baxi: boiler error codes (list for engineers)
- Baxi: what do error codes E23, E53, E133, E119 or E128 mean
- Baxi: how to reset a Baxi boiler
Last reviewed September 2026. Manufacturers update their pages, and your manual is the final word.