Main E133 means the boiler has locked out because it has not established or maintained the expected gas flame. Baxi’s current error-code reference, which includes Main Eco Compact Combi and System boilers, describes E133 as a gas-supply fault. The code can also be associated with ignition, flame-sensing or condensate conditions, so it does not prove that one particular part has failed.
You may lose both heating and hot water. Keep the boiler casing closed, check the exact model, and make only the simple external checks below.
What does Main fault code E133 mean?
The boiler has attempted to fire but its safety controls have not confirmed normal combustion. It therefore stops and shows E133 rather than repeatedly trying to run.
On the Main Eco Compact ranges included in Baxi’s current table, the manufacturer groups E133 under a gas-supply fault. Baxi’s homeowner reset guidance also says the display can point to the gas supply, ignition or flame, or a blocked condensate route. An engineer still needs to test the appliance before naming the cause.
Which Main boilers use E133?
The current Baxi error-code reference includes Main Eco Compact Combi and Main Eco Compact System within the appliance group that uses E133. Main products are now supported within Baxi’s current range and literature.
Codes vary between boiler generations. Confirm the complete model name from the appliance label and use the matching user guide. If the display includes other symbols or alternates between codes, photograph or write down the full sequence.
Safe checks before booking a repair
- Check another gas appliance, if you have one. If that is also not working, the issue may affect the property’s gas supply rather than only the boiler.
- Check a prepayment meter has credit.
- Check the gas supply has not been turned off at the meter. Do not dismantle, adjust or test any gas pipework.
- In freezing weather, look at the external condensate pipe from a safe position. If it is visibly frozen and accessible from ground level, follow the manufacturer’s homeowner instructions only. Never use boiling water.
- Try one reset exactly as described in the correct Main user guide.
If E133 returns, repeated resets are not a repair. Leave the appliance alone and arrange professional attention.
What can cause E133?
Possible causes include an interrupted gas supply, an ignition or flame-proving problem, a condensate blockage, or another internal fault affecting the ignition sequence. The code is a starting point, not a parts list.
Do not remove the case, clean or reposition electrodes, adjust the gas valve, test internal wiring, or open internal condensate components. Those checks belong with a Gas Safe registered engineer.
When is E133 an emergency?
If you smell gas, suspect a leak, or a carbon-monoxide alarm sounds, do not reset the boiler. Avoid operating electrical switches, leave the property, and call the National Gas Emergency Service on 0800 111 999 from a safe place.
Also stop using the appliance if you see scorching, flue damage, water entering the casing, or fumes. A normal-looking E133 display without those warning signs still needs a repair if it does not clear after the permitted reset.
Does E133 mean the boiler needs replacing?
No. E133 describes a lockout condition; it does not determine the cost or outcome. Many faults behind the code are repairable. The right decision depends on the confirmed cause, the boiler’s age and condition, parts availability and its maintenance history.
When booking, provide the model name, the exact display, when the fault started, and whether it appears during heating, hot-water demand or both. That gives the repair visit a useful head start.
Get your Main E133 fault fixed
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Main E133: the short answer
E133 is a gas-supply or flame-establishment lockout on the Main Eco Compact models covered by current Baxi guidance. Check the external supply, follow the exact user guide, and try one permitted reset. If the code returns, keep the casing closed and book a Gas Safe registered repair.