Chaffoteaux 270 Fault Code: Causes, Fixes & Repair Costs
What does the Chaffoteaux 270 fault code mean?
If your Chaffoteaux boiler is showing '270' on its display, it is worth knowing that this number is not a verified, publicly documented fault code within the Chaffoteaux range — the number 270 is actually associated with Baxi boilers, where it signals a dry-fire or low water pressure condition. On a Chaffoteaux boiler, you may be seeing a misread of the closely related code E27, which is well-documented across multiple Chaffoteaux model ranges including the Pigma, Urbia, Talia, and Niagara. E27 means the boiler's room temperature sensor (an NTC thermistor) is showing an open circuit — the electrical path through the sensor has broken, so the boiler cannot read the ambient temperature and may shut down or limit operation as a precaution. Related sensor codes on Chaffoteaux boilers include E29 (room sensor short circuit), E30 (underfloor heating thermostat open circuit), E33 (flue pipe sensor open circuit), E34 (flue pipe sensor short circuit), and E35 (flue pipe temperature too high). If you are genuinely unsure which code your boiler is displaying, check the fault table in your model's manual — older Chaffoteaux models such as the Britony Combi SE use LED flash-pattern codes rather than a numeric display.
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
- Faulty NTC thermistor sensor Common
The room temperature sensor itself has failed electrically. NTC thermistors measure temperature by changing their electrical resistance, and over time they can develop internal faults — the resistance either reads zero (indicating a short) or breaks the circuit entirely (open circuit). At 25°C the healthy resistance for a Chaffoteaux-compatible sensor is typically 8.1–8.6 kΩ; anything outside this range points to a failed sensor.
- Loose or corroded wiring connections Common
The connector linking the room sensor to the boiler's PCB can work loose over time, especially if the boiler has experienced vibration or the sensor lead has been disturbed. Even slight movement can be enough to break the circuit and trigger the open-circuit fault. Corrosion at the terminal pins can produce the same effect without the connector physically pulling away.
- Damaged wiring loom between sensor and PCB Sometimes
The cable running from the room sensor back to the control board may have chafed against a sharp edge, been pinched during a previous service, or simply degraded over many years of heat cycling. A broken conductor within an otherwise intact-looking cable is a common cause that is easy to miss on visual inspection alone.
- PCB fault Rare
If the NTC sensor tests within specification and all wiring checks out, the fault may lie with the printed circuit board itself. The PCB may show visible signs of overheating, scorching, melted components, or hairline cracks, or it may have failed internally without obvious visual clues. PCB faults are less common than sensor or wiring issues but should be investigated once simpler causes are ruled out.
How to fix it
- Check your boiler model and confirm the code DIY safe
Before doing anything else, locate your boiler's model number — usually on a sticker inside the front casing or in your installation manual. Cross-reference the code on screen against your specific model's fault table. If your display shows '270' rather than 'E27', it is worth confirming whether you may have a Baxi boiler rather than a Chaffoteaux, as 270 is a Baxi dry-fire/low pressure code and would need a different diagnosis.
- Reset the boiler once or twice DIY safe
Press and hold the reset button as described in your boiler's user guide. A single transient fault can sometimes trigger the error without an underlying component failure. Limit resets to two or three attempts — repeatedly resetting a boiler with a genuine fault will not fix it and some Chaffoteaux models restrict the number of resets as a safety measure. If the code returns immediately after resetting, move on to the next steps.
- A Gas Safe engineer should inspect and test the wiring connections Gas Safe engineer
With the boiler isolated from the power supply, an engineer will check the room sensor connector and the wiring loom for loose pins, corrosion, chafing, or breaks. A multimeter set to resistance measurement mode is used to check continuity along the cable and confirm the circuit is intact between sensor and PCB.
- A Gas Safe engineer should test the NTC thermistor sensor Gas Safe engineer
Using a multimeter in resistance mode, the engineer will measure the sensor's resistance at a known ambient temperature. At roughly 25°C the expected reading for a compatible Chaffoteaux/Ariston sensor is 8.1–8.6 kΩ. A reading of zero indicates a short circuit; a reading of infinite resistance or significantly outside the expected range confirms the sensor has failed and needs replacing.
- A Gas Safe engineer should replace the NTC sensor if faulty Gas Safe engineer
Compatible Chaffoteaux/Ariston NTC thermistor sensors (e.g. part number 61000733) are available from UK heating parts suppliers at around £11–£35 for the part. Replacement is straightforward once the correct sensor is confirmed, and the boiler should be re-tested after fitting.
- A Gas Safe engineer should inspect the PCB if the sensor and wiring are both fine Gas Safe engineer
If the sensor reads correctly and all wiring is intact but the E27 fault persists, the engineer will inspect the control board for visible damage — scorching, melted components, cracks, or signs of overheating. Internal PCB failure without visible signs is also possible and may require the board to be replaced or sent for specialist repair.
- Call a Gas Safe registered engineer if you have not already done so DIY safe
All diagnostic and repair work beyond a simple boiler reset must be carried out by a Gas Safe registered engineer — it is a legal requirement in the UK. You can find registered engineers at the Gas Safe Register website (gassaferegister.co.uk). When booking, mention the fault code displayed and your boiler model so the engineer can come prepared with likely replacement parts.
Parts you may need
- NTC thermistor room sensor (Ariston/Chaffoteaux compatible, e.g. part no. 61000733) · from £18
- Room sensor wiring loom/connector harness · from £25
- Chaffoteaux replacement PCB (model-dependent) · from £280
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 £100–£280, depending on the underlying cause.
Frequently asked questions
Is 270 actually a Chaffoteaux fault code?
Not as far as any publicly available documentation confirms. The number 270 is a recognised fault code on Baxi boilers, where it indicates a dry-fire condition caused by insufficient water pressure in the system. If your boiler is a Chaffoteaux and its display is showing something close to 270, it is most likely the E27 code (room sensor open circuit) — possibly misread on the display — or a model-specific code not listed in publicly available sources. Check your boiler's model number and consult your manual's fault table to be certain.
Can I fix a Chaffoteaux E27 fault myself?
The only steps a homeowner can safely carry out are resetting the boiler (no more than two or three times) and confirming the code against their model's manual. All testing, wiring inspection, and component replacement must be done by a Gas Safe registered engineer. It is a legal requirement in the UK for gas appliance repair work to be carried out by someone on the Gas Safe Register.
How much does it cost to fix a Chaffoteaux E27 room sensor fault?
For most people, the repair comes to roughly £100–£280 including the engineer's callout, labour, and the replacement NTC sensor (the sensor part itself typically costs £11–£35). If the fault turns out to be a wiring issue, costs are often at the lower end of that range. A PCB replacement — which is only needed in a minority of cases — can add considerably more to the bill, typically £180–£400 for the board alone depending on the model, so it is worth confirming the root cause before committing to that repair.
What are the other sensor-related fault codes on Chaffoteaux boilers?
Several E-series codes on Chaffoteaux boilers relate to temperature sensors and thermistors: E27 is a room sensor open circuit, E29 is a room sensor short circuit, E30 indicates an underfloor heating thermostat open circuit, E33 is a flue pipe sensor open circuit, E34 is a flue pipe sensor short circuit, and E35 means the flue pipe temperature has risen too high. If your boiler is displaying one of these rather than E27, the diagnostic approach is similar but the specific sensor location will differ — an engineer will advise on which component needs attention.