Baxi E270 fault codewhat it means and how to fix it
Baxi's dry-fire circulation fault: the heat exchanger was heating with too little water passing through it. Air, a stopped pump or a closed circuit; not a code to reset repeatedly.
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What E270 means
E270 is printed as "Circulation fault (Dry fire)" in the 600, 800, Compact and Duo-tec 2 tables and simply "Dry fire" on Baxi's professional page. It is the third of Baxi's circulation codes on the digital-display boilers, alongside E109 (before ignition) and E125 (after it), and the name says what the board has concluded: the burner was alight and the temperature at the heat exchanger climbed in a way that only happens when there is little or no water in it to absorb the heat.
Baxi do not include 270 in the list of codes they say can be relit from the panel — that list is "09, 15, 110, 125, 128, 133, 134, 135, 384" — and the user guide's general rule for a code with the spanner symbol is that it "cannot be reset by the user. Please contact your Installer, Annual Service Provider or Baxi Customer Support". The causes are the circulation set with the emphasis shifted towards the severe end.
A heat exchanger that is dry-firing has usually either lost its water (a system that has emptied through a leak faster than the pressure switch caught it, or a boiler drained and refilled with a large air pocket left in the exchanger) or has a pump that has stopped completely while the burner continued for a few seconds. Dry firing is hard on an aluminium heat exchanger, which is why the boiler does not let you clear it and try again. Check the pressure gauge before anything else; if it is in the red the code and the leak are the same problem.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| System very low on water | A leak that has taken the pressure to the bottom of the gauge, or a system drained for work and not fully refilled. The exchanger has air where the water should be and heats instantly. | Common |
| Large air pocket after refilling | The 600 user guide says the de-aeration function must be repeated after any drain. An exchanger with air trapped at the top runs dry across that section even with the pump running. | Common |
| Pump stopped | A pump that has seized or lost its supply leaves the water in the exchanger stationary, and it boils locally within seconds of the burner lighting. Baxi part 7684006 on the 600 and 800. | Occasional |
| Flow sensor reading falsely | A sensor with a poor connection can report a temperature spike that never happened. Baxi's circulation flow checks the flow sensor connections and its cold resistance of about 10 kΩ at 25 °C. | Rare |
Can you fix it yourself?
Stop — this needs an engineer
What it costs to fix
Typical repair cost
£0–£600
Time on site
1 hour
Repressurising costs nothing. Venting and a pump check £80–£120. Pump £200–£320 fitted. A heat exchanger damaged by repeated dry firing £450–£600.
Typical UK prices including parts and labour, updated September 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.
Expansion vessel (8 litre, sealed system)
EV-8L£35–£85Plumbing merchant
Price checked 28 September 2026
Baxi / Potterton / Main NTC temperature sensor (flow, return or DHW)
7207471£18–£45Authorised Baxi parts distributor
Price checked 28 September 2026
Baxi / Potterton / Main pump assembly
7684006£120–£240Authorised Baxi parts distributor
Price checked 28 September 2026
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Related Baxi fault codes
- E110Stop — call an engineerThe safety thermostat has tripped on overheat — "overheat of the primary water" in Baxi's words. One reset is allowed on every generation. If it trips again, the water is not moving.Related: overheat and circulation
- E125Get it checkedBaxi's primary circulation fault, decided by two temperature tests the manuals spell out. Pump, air or a blocked filter; the pressure is usually fine.Related: overheat and circulation
- E.04.08Stop — call an engineer"Maximum safe temperature value reached": the safety thermostat has opened on a Baxi 200/400 Combi or Combi 2. Circulation first, the thermostat second, in Baxi's own order. One reset, then an engineer.Related: overheat and circulation
- E.01.17Get it checked"No water circulation (permanent)" on the Baxi 200/400 Combi and Combi 2, after H.01.18 has shown as a temporary block. Pressure, venting and the pump, in Baxi's order; reset once.Related: overheat and circulation
- E109Get it checkedPre-circulation fault on the digital-display Baxis: the board could not confirm water moving before it would light the burner. Vent the system; Baxi allow a reset from the button.Related: overheat and circulation
- E193Get it checkedPre-circulation fault on the selector-switch Baxis (Duo-tec Combi HE, Platinum, Megaflo HE A), shown as E1 then 93. Baxi offer no reset for it; the pump or air is the cause.Related: overheat and circulation
Own a Baxi boiler? Save it and its codes come first next time.
Related guides
Technical review
Not reviewed by an engineer
No engineer has read this page. Severity follows what the manufacturer publishes, and we would rather tell you that than let a byline imply a sign-off.
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
- Manufacturer support portal
This page has not been reviewed by an engineer, and we would rather tell you that than imply otherwise. The severity rating follows what the manufacturer publishes: where they say isolate the appliance and call someone, so do we.