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Quick answer
On Baxi boilers, E133 indicates an ignition failure, most often described as an interruption to the gas supply. The boiler tried to light but did not detect a flame. Common causes are no gas reaching the boiler (including a prepayment meter out of credit), a frozen condensate pipe, low gas pressure, a faulty ignition or flame-sensing electrode, or a gas valve problem. Check the gas supply and condensate pipe, then reset once or twice. If E133 comes back, a Gas Safe engineer needs to look at it.
Key takeaways
- E133 means the boiler failed to establish a flame during ignition.
- The most common cause is a gas supply problem; test the hob and check the meter first.
- A frozen condensate pipe frequently causes E133 in winter.
- Electrodes, gas valve and gas pressure faults need a Gas Safe engineer.
- Repeated E133 lockouts should not be cleared with endless resets.
What you can check
Is gas reaching the house? Try lighting the hob. If it will not light either, check the emergency control valve at the meter and, on a prepayment meter, your credit and emergency credit. See prepayment meter and boiler not working.
Is the condensate pipe frozen? If it has been freezing, look at the plastic pipe outside. Pour warm (not boiling) water over it or use a hot water bottle. Our guide to thawing a frozen condensate pipe has the full method.
Reset the boiler. Baxi boilers have a reset button or a reset option on the display. Try once and allow the boiler to complete its start-up. Our post on resetting a boiler safely explains how many attempts are sensible.
What needs an engineer
Gas pressure. An engineer can test the working gas pressure at the boiler. Undersized pipework, a faulty meter regulator or other appliances running at the same time can starve the boiler.
Ignition and flame detection. Worn or dirty electrodes are routine causes of E133, especially on boilers that have missed services.
Gas valve. A gas valve that does not open correctly will cause ignition failure. This is a gas-carrying part that only a Gas Safe engineer can test or replace.
Flue and condensate trap. Blockages here can disturb combustion.
E133 and the Baxi range
E133 appears across many current and recent Baxi models, including the 400, 600 and 800 series combis. The exact reset procedure differs slightly between models, so check your user guide. Sister brand Potterton uses similar controls on many models; see our Potterton boiler service guide.
Prevention
Most E133 faults that are not supply-related are picked up during an annual service, when the engineer inspects the burner and electrodes and checks combustion. You can book an annual boiler service with us to get it checked.
Book with Gasmaster
Baxi showing E133? Gasmaster Plumbing & Heating, Gas Safe registered (220932), repairs Baxi boilers across Stoke-on-Trent, Newcastle-under-Lyme and Biddulph. See our boiler repair service or book through our boiler service booking page.
Frequently asked questions
Is E133 always a gas supply fault?
It is the most common cause, but not the only one. Electrodes, gas pressure and condensate problems can produce the same code.
My hob works but my Baxi still shows E133. Why?
That points away from a supply failure and towards gas pressure at the boiler, electrodes, the gas valve or the condensate system.
Can I clear E133 on my Baxi myself?
You can reset it after checking the supply and condensate. If it keeps returning, stop and call an engineer.
Sources
- Baxi, user and installation manuals (baxi.co.uk)
- Gas Safe Register (gassaferegister.co.uk)
- Health and Safety Executive, gas safety guidance (hse.gov.uk)
Related services
Abdul runs Gasmaster Plumbing & Heating and has worked on boilers, heating and gas appliances across Stoke-on-Trent since 2005. He is Gas Safe registered (reg. 220932), and these articles come from his day to day work in homes and businesses across Staffordshire, Cheshire and Derbyshire.
