Baxi E133 fault codewhat it means and how to fix it
The boiler failed to establish a flame and has locked out on the gas valve. Do not reset it more than twice.
Stop — this needs an engineer
Get a Gas Safe registered engineer to look at your Baxi E133
Gas Safe Register engineers only. No obligation.
What is the weather doing, and what else uses gas?
The right answer depends on what you can see. Pick the one that matches.
Choose the option on the left that matches what your appliance is doing, and the answer for that case appears here.
It is below freezing and the boiler worked yesterday
A frozen condensate pipe is the overwhelming favourite. It is the single most common winter Baxi call-out.
Pour warm water along the external white plastic pipe — never boiling, which can crack it — and reset once.
Other gas appliances are not working either
No gas at the property. The boiler is behaving correctly.
Check the meter valve and any prepayment credit, then call your supplier.
Gas is fine everywhere else and it is not cold
The fault is inside the boiler — most likely the electrode, possibly the gas valve.
Book a Gas Safe registered engineer and stop resetting.
You can smell gas
Stop. Do not reset, do not touch light switches.
Leave the property, open windows on the way out, and call 0800 111 999.
What E133 means
E133 is a gas supply or ignition failure lockout. The boiler ran its ignition sequence and did not confirm a flame, so it shut the gas valve and latched the fault rather than trying indefinitely. That behaviour is deliberate: an appliance that keeps attempting ignition keeps putting unburnt gas into a combustion chamber. In practice the causes fall into three groups — no gas arriving at the appliance, an ignition or flame sensing electrode that has degraded, or a condensate pipe blocked with ice. The last is seasonal and by far the easiest for a householder to check.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| No gas at the appliance | Empty prepayment meter, closed service valve, or a supply interruption. | Common |
| Frozen condensate pipe | Baxi condensate runs are often long and horizontal. The first hard frost ices them up and the boiler cannot complete a cycle. | Common |
| Ignition or flame sensing electrode degraded | Carbon build-up stops the electrode detecting the flame it has lit. | Common |
| Gas valve fault | Not opening, or opening too slowly for the ignition window. | Occasional |
Can you fix it yourself?
Stop — this needs an engineer
What it costs to fix
Typical repair cost
£0–£450
Time on site
1 hour
Thawing a condensate pipe is free. Insulating and re-routing it £120–£250. Electrode £130–£220. Gas valve £280–£450.
Typical UK prices including parts and labour, updated August 2026. Your quote may differ.
Parts you may need
We may earn a commission if you buy a part through one of these links. It does not change what you pay, and it does not affect which parts we list.
Ideal Logic ignition electrode
175565£18–£42Authorised Ideal parts distributor
Price checked 5 August 2026
Condensate trap and siphon
COND-TRAP£15–£38Plumbing merchant
Price checked 5 August 2026
What other owners found
Nobody has shared what worked for them on this code yet. If you have had it, you would be the first — and it genuinely helps the next person.
Related Baxi fault codes
- E128Get it checkedThe flame has been repeatedly lost during operation. That is a different problem from failing to ignite.Related: ignition and gas supply
- E168Get it checkedA control board lockout. Baxi note it often follows a power supply problem, so a proper power cycle is worth trying first.Related: ignition and gas supply
- EA 227Stop — call an engineerThe boiler tried to light and never detected a flame, so it has shut the gas off and locked out. This is the most common Worcester fault code.Related: ignition and gas supply
- E01Get it checkedThe appliance tried to light and could not confirm a flame, so it has locked out. In winter a frozen condensate pipe is the most likely reason.Related: ignition and gas supply
- F.28Stop — call an engineerThe boiler tried to light and failed three times in a row, so it has shut the gas off and locked out. Do not keep resetting it.Related: ignition and gas supply
- 501Get it checkedNo flame was detected during ignition and the appliance has locked out. Check the gas supply and the condensate pipe before booking anyone.Related: ignition and gas supply
Related guides
Common questions about Baxi E133
How do I thaw a frozen condensate pipe safely?
Use warm water from a kettle that has been left to stand, or a hot water bottle held against the pipe. Never use boiling water — the thermal shock can crack the plastic and turn a free fix into a plumbing job. Pour along the length of the pipe, not just at one point.
Why does the condensate pipe keep freezing?
Because it is too small, too long, or has too little fall. The permanent fix is to increase the pipe diameter outside, insulate it, and reduce the horizontal run. That costs £120 to £250 and stops it happening every winter.
How many resets are safe?
Two. Each reset starts a new set of ignition attempts, and each attempt releases a little gas before the valve shuts. If two have not worked, the fault is real.
Sources and how we verified this
We establish the facts from the sources below and then write the explanation ourselves. We do not copy manufacturer wording and we do not host their manuals.
- Manufacturer technical and service documentation
- Trade body guidance
- Interviews with working engineers
Checked by Technical reviewer (Gas Safe registration to be displayed on appointment) on 5 August 2026.