Chaffoteaux 210 Fault Code: Causes, Fixes & Repair Costs
What does the Chaffoteaux 210 fault code mean?
Fault code 210 on a Chaffoteaux boiler points to a problem detected within the domestic hot water (DHW) temperature sensor circuit. The boiler's PCB monitors the NTC thermistor that measures hot water temperature; when it receives a signal outside its expected range — caused by a short circuit, open circuit, or erratic resistance reading — it triggers this code and may suspend hot water production as a safety precaution. At room temperature (around 25°C), a healthy Chaffoteaux NTC sensor should read between 8.1 and 8.6 kΩ; a reading of 0 Ω suggests a short, while infinite resistance indicates a broken circuit. This code belongs to the 200-series family of DHW and cylinder sensor faults that appear across several Chaffoteaux ranges — including the Talia, Pigma, Urbia, and Niagara — so always confirm the code against your specific model's manual. Related codes in the same family include 201 (DHW/sanitary sensor anomaly) and 203 (cylinder/ballon probe anomaly); fault 210 typically indicates a full sensor or wiring failure rather than a marginal reading.
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
- Failed DHW NTC thermistor Common
The NTC sensor itself has developed an internal break or short circuit, sending the PCB a reading it cannot interpret. This is the single most common reason for a 210 code. A resistance check with a multimeter will confirm whether the sensor is open-circuit (infinite resistance), short-circuit (0 Ω), or out of tolerance at rest temperature.
- Loose, corroded, or damaged wiring at the sensor connector Common
Vibration, condensation, and age can cause the connector at the DHW sensor to work loose or corrode. Oxidised terminals create an unstable resistance signal that the PCB reads as a fault even when the thermistor itself is still functional. Intermittent 210 faults that clear on reset then return are a classic sign of a connection problem.
- Limescale accumulation on the sensor or heat exchanger Sometimes
In hard-water areas, mineral deposits coat the sensor's surface, reducing its thermal contact with the water and distorting its readings. Heavy scaling on the DHW heat exchanger also restricts flow, which can cause temperature spikes that the sensor circuit registers as anomalous.
- PCB fault Sometimes
If the sensor and all its wiring test within specification but the 210 code persists, the PCB itself may be misreading the sensor signal due to a failed input circuit, corroded tracks, or heat damage to the board. Look for visible signs such as discolouration, swollen capacitors, or burnt tracks around the sensor input terminals.
- Electrical supply irregularity Rare
Voltage spikes or unstable mains supply can corrupt the PCB's sensor readings and trigger spurious fault codes. A single unexplained 210 that never returns after a reset may have been caused by a momentary supply fluctuation rather than a hardware fault.
How to fix it
- Reset the boiler once or twice DIY safe
Press and hold the reset button on the boiler's front panel as described in your user manual. Wait for the boiler to complete its ignition sequence. If the 210 code returns immediately or after a short time, a reset alone will not fix it and you should proceed to the next steps. Do not keep resetting repeatedly — two or three attempts is the sensible limit.
- Check that your gas and electricity supplies are normal DIY safe
Confirm that other gas appliances (hob, gas fire) are working normally and that no other circuits in your home have tripped. An interruption to the electrical supply can cause transient sensor errors on Chaffoteaux boilers. If supplies look fine, the fault is almost certainly inside the boiler.
- Visually inspect the boiler for obvious issues DIY safe
With the boiler switched off at the isolator, look through any access panels for obvious problems such as signs of water leakage near the DHW sensor location, or heavily corroded pipework. Do not touch internal components, gas pipework, or electrical wiring. If you see anything concerning, turn off the boiler and call an engineer straightaway.
- Have a Gas Safe engineer test the DHW NTC sensor resistance Gas Safe engineer
An engineer will disconnect the sensor connector and use a calibrated multimeter in resistance mode to check the thermistor's reading. At approximately 25°C it should read 8.1–8.6 kΩ. A reading of 0 Ω confirms a short circuit; an open-circuit (OL) reading confirms a broken sensor. They will also inspect the connector terminals for oxidation or mechanical damage and clean or replace them as needed.
- Have a Gas Safe engineer replace the DHW NTC sensor if faulty Gas Safe engineer
If the sensor is out of specification, the engineer will fit a replacement Chaffoteaux-compatible NTC thermistor. The part itself is relatively inexpensive (typically £10–£40 depending on the exact part number), and the job is usually completed within an hour. After fitting, the engineer will reset the boiler and confirm the 210 code has cleared.
- Have the PCB inspected and replaced if the sensor tests correctly Gas Safe engineer
If the sensor and wiring are both in good condition but the fault persists, the PCB is the next suspect. An engineer will carry out further diagnostics before recommending a board replacement, as PCBs are a higher-cost repair. Confirm they are fitting a genuine or manufacturer-approved replacement part.
- Book a Gas Safe registered engineer if the fault has not cleared Gas Safe engineer
If you have not been able to resolve the fault through the homeowner-safe steps above, contact a Gas Safe registered engineer. You can verify any engineer's registration at GasSafeRegister.co.uk before they arrive. Do not attempt to use the boiler for hot water if it has locked out on this fault code.
Parts you may need
- Chaffoteaux DHW NTC thermistor (e.g. part 61000733 or equivalent) · from £15
- Sensor wiring harness/connector · from £20
- Chaffoteaux PCB (model-dependent) · from £220
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
Can I still use my heating even though fault code 210 has appeared?
It depends on how your boiler responds. Because code 210 relates specifically to the domestic hot water sensor circuit, some Chaffoteaux models will suspend DHW production but continue to run the central heating. Others may lock out completely as a precaution. Check whether your radiators are still heating up. Either way, you should arrange for a Gas Safe engineer to diagnose and fix the fault promptly rather than leaving it running in a degraded state.
How much does it cost to fix a Chaffoteaux 210 fault code in the UK?
For the most common repair — replacing a faulty DHW NTC sensor — expect to pay roughly £100–£280 in total, covering the part (£10–£40) and an engineer's time (typically one hour). If the fault turns out to be the PCB, costs are higher: a replacement PCB for a Chaffoteaux boiler typically runs £180–£300 for the part alone, with total costs including labour often reaching £350–£500. Always get a written quote before work begins.
What is the difference between Chaffoteaux fault codes 201, 203, and 210?
All three fall within the 200-series DHW sensor fault group. Code 201 flags an anomaly on the main DHW (sanitary) sensor and often indicates the sensor needs replacing. Code 203 relates to the cylinder or ballon probe — the sensor that monitors stored hot water temperature in an indirect cylinder. Code 210 indicates a more definitive fault in the DHW temperature sensor circuit itself, such as a full open circuit or short circuit, rather than just a marginal or drifting reading. If you are unsure which applies to your specific model, check your installation manual or ask your engineer.
How do I prevent the DHW sensor from failing again?
Annual servicing by a Gas Safe registered engineer is the single most effective preventive measure — Chaffoteaux themselves recommend yearly servicing. During a service the engineer will check sensor readings, inspect connections, and identify early signs of corrosion or scale build-up before they cause a breakdown. If you live in a hard-water area, fitting or maintaining a scale reducer on the cold-water supply to the boiler will help protect the DHW heat exchanger and sensors from limescale damage over time.