When a Baxi boiler stops, it usually shows an E-code on the display telling you why. This guide explains the most common Baxi faults in plain English, the handful of checks you can safely do yourself, and exactly when the job belongs to a Gas Safe registered engineer.
Baxi is one of the UK's longest-established boiler brands, and modern combi, system and heat-only models — including the popular 600, 800 and Platinum ranges — flash a fault code on the front panel when they lock out. The codes nearly always start with an "E" followed by a number (for example E1, E110 or E133). The "E" simply stands for error; the number identifies the specific fault the boiler's control board has detected.
A lockout isn't the boiler breaking for no reason — it's the boiler protecting itself and you. Rather than carry on running with a sensor reading, a flow problem or an ignition fault, it stops and shows the code. The trick is reading the code correctly, because the exact meaning can shift slightly between models and generations. The label inside your boiler's casing flap, or your user manual, is always the final word for your specific unit.
The table below covers the Baxi codes homeowners ask about most. Each row gives the plain-English meaning and a link to a dedicated guide with the full causes, safe checks and indicative repair costs. Treat this as general guidance, not a diagnosis for your exact model.
| Code | What it usually means | Read more |
|---|---|---|
| E1 | Low water pressure or no flow — the boiler can't sense enough water moving when it tries to fire. | E1 fault code |
| E20 | Primary flow temperature sensor fault — the sensor reading the central-heating flow temperature is out of range or has failed. | E20 fault code |
| E28 | Flue gas thermistor fault — the sensor monitoring flue temperature is reading incorrectly, so the boiler shuts down. | E28 fault code |
| E110 | Overheat lockout — the boiler has detected too high a temperature and shut down to protect itself, often poor flow or a stuck pump. | E110 fault code |
| E119 | Low system pressure — water pressure has dropped below the safe minimum (around 1 bar) so the boiler won't fire. | E119 fault code |
| E133 | Gas / ignition fault — the boiler attempted to light but no flame was established (gas supply, ignition or flame-detection issue). | E133 fault code |
| E160 | Fan fault — the combustion fan isn't running at the expected speed, or its signal isn't being read. | E160 fault code |
If your code isn't listed, don't guess from a similar-looking one — the same number can mean different things across the 600, 800 and Platinum generations. Check the meaning printed in your boiler's own manual or on the inside of the casing flap.
Only a short list is genuinely DIY. Anything that touches the gas valve, the burner, the flame-sensing electrode, the flue or the sealed combustion circuit means taking the casing off and using test equipment — that is Gas Safe registered engineer work only, and it is both illegal and dangerous for an unregistered person to attempt. The homeowner-safe checks are:
For a lockout code, you can press and hold the reset button on the Baxi front panel for a few seconds to restart the sequence. Do this only once.
For a low-pressure code such as E1 or E119, repressurising via the filling loop is a safe homeowner job. The gauge should read about 1 to 1.5 bar when cold, rising towards roughly 2 bar when hot. Below about 1 bar is low.
If the pressure keeps falling over days or weeks, you have a leak or an expansion-vessel fault that needs an engineer — not endless topping up. Our guide to low boiler pressure explains what to look for.
The pattern is consistent across Baxi faults: the water-side checks (pressure, bleeding radiators, power and controls) are yours; everything behind the casing is an engineer's. Call a Gas Safe registered engineer when:
You can confirm any engineer's registration, including the specific gas appliances they're qualified for, at gassaferegister.co.uk. The Gas Safe Register replaced the old CORGI scheme in 2009 and is the only legal register for gas work in the UK. Never attempt work on the gas valve, pipework, flue, sealed circuit, pressure relief valve or anything behind the casing yourself.
Most of the faults in this guide — a failed sensor, fan, pump or gas valve — are engineer-only repairs that can run from one to several hundred pounds as a one-off bill. That's where a policy earns its keep. With boiler cover, a breakdown like an E160 fan fault or an E133 ignition fault is handled for the price of your monthly premium, and an approved engineer is sent out rather than you sourcing one yourself.
Cover isn't right for everyone, and the value depends on your boiler's age, the excess and what's excluded. Our guides to the best boiler cover and whether boiler cover is worth it walk through how to weigh it up. We're a comparison site showing a selected panel of providers, not the whole market — so always read each policy's terms before you buy.
A single fan, pump, sensor or gas-valve job can run to several hundred pounds. Compare boiler-cover plans side by side and see what a fixed monthly premium would protect you against.
Compare boiler coverWhen a Baxi locks out it stops firing, so there's no immediate hazard from the lockout itself — but you'll have no heating or hot water until it's fixed. If you ever smell gas, see soot or scorching, or a CO alarm sounds, don't reset it: leave the property and call 0800 111 999.
You can reset a lockout once from the front panel, repressurise if it's a low-pressure code such as E1 or E119, bleed radiators and thaw a frozen condensate pipe. If the code returns after one reset, stop — the remaining causes (sensors, fan, ignition, gas valve, overheat) need a Gas Safe registered engineer with the casing off.
A repeating code means the underlying fault hasn't been fixed — a failing fan on an E160, a sensor on an E20 or E28, an ignition problem on an E133. Repeated resets won't cure it and can make things worse, so get it diagnosed rather than cycling the reset button.
Don't assume it matches a similar code. The exact meaning varies across the Baxi 600, 800 and Platinum ranges. Check the fault-code list in your boiler's manual or on the label inside the casing flap, which is the only reliable source for your specific appliance.
Most heating-repair policies cover parts and labour for faults like these, subject to the boiler being in good working order when you took the policy out, the boiler-age limit, and any excess on the plan. Always check the exclusions before you buy.