What it means
In freezing weather, Baxi's frost advice links E133 to a frozen condensate pipe. You may hear gurgling from the boiler before it shuts down. On some displays the code alternates between E1 and 33.
What to check, in order
- Make sure the gas supply is on
Baxi lists a gas supply problem as one of the causes. The boiler can't light without gas.
- 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. If it's still frozen, Baxi says to repeat the thawing until the boiler 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 still won't light, or it locks out often, call a Gas Safe registered engineer. Baxi says frequent lockouts mean there's a fault.
Good to know
- Baxi's frost advice says a boiler showing E28, E53, E119 or E128 may also have a frozen condensate pipe.
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 E133 fault code mean?
The boiler tried to light and couldn't, so it has locked out. Baxi says E133 points to a problem with the gas supply, the ignition or flame, or a blocked condensate pipe. In freezing weather, Baxi's frost advice links E133 to a frozen condensate pipe. You may hear gurgling from the boiler before it shuts down. On some displays the code alternates between E1 and 33.
Can I fix Baxi E133 myself?
Easy (about 30 minutes). Start with: make sure the gas supply is on; in cold weather, thaw the condensate pipe; power on and restart. If it still won't light, or it locks out often, call a Gas Safe registered engineer. Baxi says frequent lockouts mean there's a fault.
Is Baxi E133 worth repairing?
Worth fixing. In cold weather, a frozen condensate pipe is a common cause and costs nothing to thaw. If it isn't that, an engineer needs to look at the gas supply to the boiler and the ignition.
Checked against
- Baxi: how to reset a Baxi boiler
- 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.