Baxi E270 Fault Code: Causes, Fixes & Repair Costs
What does the Baxi E270 fault code mean?
The E270 fault code on Baxi boilers signals a circulation problem, commonly described as a 'dry fire' condition. This means the boiler's controls have detected that water is not flowing through the system correctly — or that flow temperatures are behaving abnormally — and the boiler has locked out as a safety measure to prevent damage. It will not restart until the underlying issue is resolved and the fault is cleared. The precise trigger can vary slightly between models: on the Baxi 600 Series, E270 may relate to a DHW (domestic hot water) pressure fault, while on the Baxi Megaflo it can indicate a DHW temperature fault. Despite these nuances, the root cause — inadequate or abnormal water circulation — is consistent across the range.
General guidance only — not a substitute for professional advice, and not certified by a Gas Safe engineer. Always have your specific appliance assessed by a qualified professional. Any gas work must be carried out by a Gas Safe registered engineer. If you smell gas or suspect carbon monoxide, leave the property and call the National Gas Emergency line on 0800 111 999.
Common causes
- Low system pressure Common
If the central heating system has dropped below around 1 bar, the boiler may not be able to circulate water properly, triggering a dry fire condition. Pressure drops are often caused by a small leak somewhere in the pipework, radiator valves, or simply natural system settling over time.
- Faulty or poorly connected water/temperature sensor Common
Sensors measuring flow temperature, return temperature, or pressure report constantly to the boiler's controls. A sensor that has developed a fault, corroded, or come loose from its connector can send readings that appear wildly out of range, causing the boiler to interpret the situation as a circulation failure even when water movement itself is fine.
- Circulation pump failure or restriction Common
The pump is responsible for pushing water around the system. If it has seized, lost speed, or is partially blocked by sludge or debris, water flow will be insufficient and the boiler will detect the resulting temperature rise as a circulation fault.
- Blocked or scaled heat exchanger Sometimes
On hard-water areas or older systems without inhibitor, limescale and sludge can accumulate inside the heat exchanger, restricting water flow. This is a particularly common trigger on the Baxi Megaflo, where restricted DHW flow can cause temperature anomalies that generate E270.
- Fan or air pressure switch fault Sometimes
The fan and its associated air pressure switch manage ventilation and flue gas removal. A wiring fault on the fan motor or a defective air pressure switch can prevent the boiler from confirming safe airflow, which in some circumstances contributes to or triggers circulation-related lockouts.
- PCB (printed circuit board) fault Rare
The PCB co-ordinates all boiler functions. If it develops a fault it may send incorrect signals to the pump, gas valve, or sensors, causing the boiler to behave as though a circulation problem exists when other components are working normally. PCB issues sometimes cause intermittent or hard-to-reproduce E270 faults.
How to fix it
- Check your gas supply is working DIY safe
Confirm other gas appliances in your home (hob, fire) are working normally. If there is no gas supply to the property, contact your gas supplier before doing anything else.
- Check the system pressure gauge DIY safe
Look at the pressure gauge on the boiler's front panel. It should read between 1.0 and 1.5 bar when the system is cold. If it reads below 1 bar, the system needs repressurising via the filling loop. Consult your boiler manual for the correct filling loop procedure, then top up slowly until the gauge reads approximately 1.2 bar and close the filling loop valves fully.
- Reset the boiler DIY safe
Press and hold the reset button for around 3 seconds, then allow the boiler to attempt a restart. If it fires up and runs normally, monitor it over the next day or two. Do not reset the boiler more than two or three times in total — repeated resetting without resolving the cause can mask a developing fault and may cause further damage.
- Check for visible leaks around the boiler and pipework DIY safe
Look underneath the boiler casing, around visible pipe joints, and behind radiators for any signs of water staining, drips, or damp patches. Even a minor weep can gradually reduce system pressure and trigger E270. Note any findings to pass on to the engineer.
- If the fault persists, call a Gas Safe registered engineer Gas Safe engineer
If the boiler locks out again after a reset, or if pressure was fine and no leak is visible, the fault lies with an internal component — most likely a sensor, the pump, the heat exchanger, or the PCB. All of these require diagnosis and repair by a Gas Safe registered engineer. Do not attempt to remove panels, access sensors, or interfere with gas or electrical components yourself.
Parts you may need
- NTC flow/return temperature sensor · from £25
- System pressure sensor · from £35
- Central heating circulation pump · from £85
- Printed circuit board (PCB) · from £180
- Air pressure switch · from £45
The exact spare depends on your boiler's GC number (on the data badge). Check this against the part before buying.
Typical repair cost
Expect to pay roughly £120–£350, depending on the underlying cause.
Frequently asked questions
Can I keep resetting the boiler to get hot water while I wait for an engineer?
You can reset once or twice to confirm the fault is persistent, but avoid repeatedly resetting the boiler as a workaround. Doing so can mask the true cause and, in a genuine circulation fault, risks running the boiler without adequate water flow, which can damage the heat exchanger. If it locks out again after one or two resets, leave it off and book an engineer promptly.
Why does E270 mean something different on the Baxi 600 Series compared to the Megaflo?
Baxi uses the same error code across multiple product lines, but the sensor or circuit being monitored differs by model. On the 600 Series, E270 is more closely tied to DHW circuit pressure readings, whereas on the Megaflo (an unvented cylinder-based system) it typically relates to DHW temperature monitoring. In both cases the boiler has detected an abnormal condition in the water circuit and locked out for safety. An engineer familiar with your specific model will know exactly which sensor or parameter to test first.
How much does it cost to fix an E270 fault on a Baxi boiler?
Most E270 repairs fall in the range of £120 to £350 including parts and labour. A straightforward sensor replacement or pump service sits at the lower end, while a pump replacement or heat exchanger clean typically costs £200–£350. PCB replacement is a less common cause but can cost £350–£500 or more depending on the model — if your engineer suspects the PCB, ask for a written quote before authorising the work.
Could low boiler pressure alone cause an E270 lockout?
Yes, particularly on the Baxi 600 Series where the fault is linked to DHW pressure monitoring. If the system pressure has dropped below around 1 bar, the boiler may not be able to confirm adequate water circulation and will lock out with E270. Topping up the system pressure to 1.2–1.5 bar via the filling loop and then resetting the boiler will resolve the fault if low pressure was the sole cause. If pressure looks normal or the fault returns shortly after repressurising, an engineer needs to investigate further.