E110 on a Baxi boiler means the safety thermostat has tripped because the water inside the boiler, or the flue, got too hot. It nearly always comes down to water not moving through the boiler fast enough: a failing pump, air, low pressure, sludge or a closed valve. If an older Baxi keeps locking out with E110, a new Baxi boiler is usually the better long-term option, both for efficiency and for lower repair bills.
We’re Clever Energy Boilers, a Gas Safe registered (no. 554138) installer in Bingley, accredited by Worcester Bosch and fitting boilers across Yorkshire, the North West and the Midlands. More than 25,000 installations over 15 years means overheating codes are a familiar sight. This guide explains what E110 means on each Baxi, why it happens, what you can safely check and when it points to a new boiler.
What does the Baxi E110 error code mean?
Baxi’s own description is “safety thermostat operated”. The primary water (the water that runs round the boiler and your radiators) or the flue has overheated, and the boiler has locked out until it’s reset. That’s the meaning on the Platinum, Duo-tec, Main Eco and Assure. On the 600 Combi (624 and 630) it means the primary water has overheated.
Baxi’s newer dotted-code boilers use H.01.05 and H.01.08 for the same fault, and our Baxi boiler error codes guide shows how the old codes map to the new ones. Seen it written as “E1 10”? That’s the same code read in two halves, as our Baxi E1 decoder explains.
Baxi EcoBlue E110 vs E111: pump fault or overheat?
The EcoBlue splits the fault into two codes:
- E110 points to a pump fault
- E111 means the boiler has gone over temperature
That split tells your engineer where to start, with the pump or with why the boiler is running too hot. Most fault code lists treat E110 as one generic fault and miss it.
Why is my Baxi boiler showing an E110 fault?
The usual causes, most likely first:
- A seized or failing pump. If the pump can’t move the water, heat builds up inside the boiler. Radiators that stay cold can be a clue, as our guide to radiators not heating up explains.
- Air in the system, which blocks the flow. See our guide to a boiler airlock.
- Low water pressure. With too little water in the system, there’s nothing to carry the heat away. Our guide to a boiler losing pressure covers why it drops.
- Sludge or a blocked filter. Sludge builds up over the years and clogs the system. A magnetic boiler filter catches it, but only if someone cleans it.
- Scale on the heat exchanger, stopping heat passing into the water. See heat exchanger faults.
- Closed valves left shut after decorating or work on the heating.
- A faulty sensor or safety thermostat. Sometimes the part reporting the overheat is the part that’s failed.
Is the Baxi E110 fault dangerous?
The lockout isn’t. It’s the safety thermostat cutting the boiler before it gets dangerously hot, which is exactly its job.
Repeated overheating is the real concern. It strains the pump and the heat exchanger, and the heat exchanger is the most expensive part in the boiler. If you ever smell gas, open the windows, don’t use any switches, turn off the gas at the meter and call 0800 111 999.
What can I safely check at home when my Baxi shows E110?
All of these are outside the casing:
- Check the pressure. With the boiler cold, the gauge should read 1 to 1.5 bar. If it’s low, here’s how to repressurise a boiler.
- Are the radiator valves open? Go round the house and make sure none have been turned off.
- Bleed the radiators, but only if you need to. Gurgling or cold tops mean air, and our guide to bleeding radiators walks you through it. Bleeding drops the pressure, so check the gauge again afterwards and top up if needed.
- Reset once. Baxi’s Platinum guide allows a reset by holding the R button for 5 seconds. If E110 comes straight back, leave it.
When should I stop resetting the E110 error and get a Gas Safe engineer?
If E110 returns after one reset with the pressure right and the valves open, stop. Each reset puts the boiler through another overheat. A Gas Safe registered engineer needs to check the pump, the filter and the heat exchanger. Never take the casing off yourself.
Why does the Baxi E110 fault code keep coming back?
Because the cause builds up gradually. Sludge collects slowly and a pump wears slowly, so the boiler copes on some days and trips on others. Topping up or bleeding a radiator can buy time, but with sludge or a tired pump behind it, E110 will be back.
Is an E110 error a sign you need a new Baxi boiler?
On an older Baxi, often. Overheating usually means sludge and a tired pump, and on a boiler more than 8 years old the heat exchanger is the next thing at risk. Typical repair costs look like this:
| Repair | Typical cost |
|---|---|
| Free off or replace the pump | £150 to £350 fitted |
| Powerflush or filter clean | Quoted by the engineer |
| Heat exchanger | £500 to £700 |
| Engineer labour | £50 to £80 an hour |
Source: MyJobQuote, October 2026.
A new pump on a young boiler is a sensible repair. A Duo-tec, Platinum or EcoBlue is now 10 years old or more, though, and on one of those it’s time to think about replacing if:
- E110 has come back after a new pump or a flush
- An engineer has flagged the heat exchanger
- You’ve had other circulation codes as well, such as E125
- Your bills are creeping up on a boiler that’s past 8 years old
Our guide to how much a new boiler costs gives you the other side of the sum.
Get a new Baxi boiler with Clever Energy
We install Baxi boilers in Bingley, Bradford, Leeds, Halifax and Keighley, whether that’s a back-to-back in Bradford or a farmhouse on the moors above Haworth, and across the North West and the Midlands. A new boiler is a good moment to deal with sludge too, so the problem behind E110 doesn’t follow you, and it can come with a long, market-leading warranty through Clever Energy. See our Baxi boiler installation page, get a fixed price online in a few minutes or request a callback. If you’d rather talk it through, call 0330 055 2210 between 8am and 8pm on weekdays or 10am to 4pm at weekends.
Baxi E110 fault code FAQs
What does E110 mean on a Baxi boiler?
The safety thermostat has operated because the primary water or the flue overheated. On the EcoBlue, E110 points to a pump fault and E111 to over-temperature.
Can I reset a Baxi E110 fault myself?
Yes, once. Check the pressure and radiator valves first, then hold R for 5 seconds, and if it comes back, call a Gas Safe registered engineer.
Why does my Baxi keep overheating?
Most often a failing pump, sludge, a blocked filter, air in the system or low pressure. A scaled heat exchanger or a faulty sensor can also cause it.
Will bleeding radiators fix a Baxi E110 error?
Only if air is the cause. Bleed them if you hear gurgling or the tops are cold, then check the pressure and top up.
Is a Baxi E110 code dangerous?
Not in itself, because the code is the boiler protecting itself. Repeated overheating can damage the heat exchanger, so don’t keep resetting it.
More Baxi error codes
Before this one, the Baxi E20 fault code covers the central heating sensor. Next in the set is the Baxi E119 fault code for low pressure, one of the causes behind E110. Every code, by model, is on our Baxi boiler error codes guide.