Intergas 22 Fault Code: Causes, Fixes & Repair Costs
What does the Intergas 22 fault code mean?
Fault code 22 on Intergas boilers (HRE, Eco RF, Rapid and related iC3 PCB models) means the boiler's control board has detected that the S2 temperature sensor — which monitors water temperature at the heat exchanger outlet — has not changed its reading over a 24-hour period, even though a heating or hot water demand was made during that time. Because a functioning system should see temperature fluctuations whenever the boiler fires, a completely static reading tells the PCB that something is wrong: either the sensor itself has failed, there is a wiring fault, or water is not circulating properly through the heat exchanger. As a safety precaution the boiler locks out and displays code 22 until the underlying problem is identified and resolved. Note: if you have an Intergas Xtreme or Xclusive model, fault code numbering differs slightly — always cross-reference with your specific model's manual.
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 S2 outlet temperature sensor Common
The S2 sensor uses an NTC (Negative Temperature Coefficient) thermistor to report heat exchanger outlet temperature to the PCB. Over time — particularly in older boilers — the thermistor degrades and its resistance drifts out of the expected range or rises to infinity, causing the PCB to log a flat, unchanging reading. This is the single most common root cause of code 22.
- Loose, corroded or damaged sensor wiring Sometimes
Even if the S2 sensor itself is still functional, a corroded terminal, loose connector plug or damaged wire between the sensor and the PCB can interrupt or distort the signal. The PCB interprets a broken signal as no temperature change, triggering the same lockout. Wiring faults are especially likely on boilers that have experienced damp ingress or are several years old.
- Poor circulation — limescale, sludge or airlocks Sometimes
If the S2 sensor is reporting accurately, then the static temperature reading reflects a real problem: water is not flowing or heating correctly through the heat exchanger. Limescale build-up (more prevalent in hard water areas), sludge deposits, an airlock, or a failing pump can all restrict flow enough that the outlet temperature never rises or falls as expected during a firing cycle.
- PCB fault Rare
In rarer cases the PCB itself misreads or fails to process the signal from the S2 sensor, generating a false code 22 even when the sensor and wiring are both intact. A PCB fault is usually only confirmed after the sensor and wiring have been ruled out.
How to fix it
- Check that your gas supply is working DIY safe
Confirm other gas appliances in your home (hob, gas fire) are working normally. If there is no gas supply at all, contact your gas supplier rather than resetting the boiler.
- Reset the boiler once DIY safe
Press and hold the reset button (or follow the reset procedure in your Intergas user guide) to attempt a restart. Limit resets to one or two attempts — repeated resets on a locked-out boiler will not clear a genuine fault and can mask the underlying problem. If the boiler fires and runs normally, monitor it closely. If code 22 returns, move to the next step.
- Check system pressure DIY safe
Look at the pressure gauge on the boiler. Intergas boilers should typically read between 1.0 and 1.5 bar when cold. If pressure is below 0.8 bar, top it up via the filling loop according to your user guide. Low pressure alone can contribute to circulation problems, though it is unlikely to be the sole cause of code 22.
- A Gas Safe engineer tests and replaces the S2 sensor if required Gas Safe engineer
The engineer will use a multimeter to measure the resistance of the S2 sensor and compare it against the expected NTC curve. If the reading is out of range or open-circuit, the sensor will be replaced with a genuine Intergas part. Fitting non-original sensors on Intergas heat exchangers is not recommended by the manufacturer and can cause further damage.
- A Gas Safe engineer inspects wiring and connector plugs Gas Safe engineer
The engineer will check the wiring loom between the S2 sensor and the PCB for corrosion, chafing or loose terminals. Corroded pins are cleaned or replaced and connectors are re-seated. This step is often carried out at the same time as sensor testing.
- A Gas Safe engineer investigates circulation, the pump and the heat exchanger Gas Safe engineer
If the sensor and wiring are both healthy, the engineer will assess water flow through the system — checking for airlocks, sludge, limescale fouling inside the heat exchanger, and pump performance. A power flush may be recommended if significant sludge or scale is found. In hard water areas, an inline scale inhibitor or magnetic filter should be fitted if not already present.
- A Gas Safe engineer tests or replaces the PCB if all other causes are ruled out Gas Safe engineer
If sensor, wiring and circulation checks come back clear, the PCB is the remaining suspect. The engineer will test it with a multimeter and, if faulty, fit a replacement. Given the cost of a new PCB (typically £400–£500 all-in), the engineer should also advise whether replacement is economical relative to the boiler's age.
- Call a Gas Safe registered engineer if the fault persists or you are unsure Gas Safe engineer
Code 22 is not a fault a homeowner can diagnose or safely repair beyond the basic checks above. Book a visit from a Gas Safe registered engineer — you can verify any engineer's registration at www.gassaferegister.co.uk using the licence number on the back of their ID card.
Parts you may need
- Intergas S2 NTC temperature sensor · from £35
- Sensor wiring loom / connector plug · from £20
- Intergas PCB (iC3 control board) · from £220
- Central heating pump · from £65
- Magnetic system filter (e.g. Adey MagnaClean) · from £55
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 reset an Intergas code 22 myself and will that fix it?
You can try a single reset — the Intergas reset function is designed to restart the boiler once a fault has been resolved, not to clear the fault itself. If the underlying S2 sensor or circulation problem has not been fixed, the boiler will simply lock out again, often within the same heating cycle or within 24 hours. Limit yourself to one or two reset attempts and call an engineer if the code returns.
How much does it cost to fix Intergas fault code 22 in the UK?
For the most common cause — a failed S2 sensor — expect to pay roughly £120–£200 including parts, labour and the call-out fee. Wiring repairs fall in a similar range. If the heat exchanger needs a power flush the bill typically rises to £250–£350. A PCB replacement is a more expensive outlier, usually £400–£500 all-in; at that level it is worth asking your engineer whether repair or a new boiler is the better long-term investment, especially if the boiler is over ten years old. Prices in London and the South East tend to run around 15–25% above the national average.
What is the S2 sensor on an Intergas boiler and where is it located?
Intergas heat exchangers have two NTC temperature sensors: S1 monitors the flow (inlet) side and S2 monitors the outlet (return) side. Together they allow the PCB to track how much heat is being transferred and to protect the boiler from overheating or flow problems. The S2 sensor sits on the heat exchanger outlet pipe and is connected to the PCB by a wiring loom. Both sensors are Intergas-specific parts and the manufacturer recommends using genuine replacements to avoid calibration errors.
My Intergas boiler is still under warranty — does code 22 affect my warranty claim?
Intergas boilers come with at least a 12-month warranty, and depending on the model and whether it was registered, this can extend to 3–10 years. If your boiler is within the warranty period, contact Intergas or your installing engineer before arranging an independent repair, as unauthorised repairs using non-genuine parts can invalidate the warranty. You can check warranty terms on the Intergas Heating UK website or by calling their technical helpline.