Vokera 06 Fault Code: Causes, Fixes & Repair Costs
What does the Vokera 06 fault code mean?
Fault code 06 (shown as A06 on newer Vokèra models, and E060 on Evolve models) tells you that the boiler's domestic hot water (DHW) thermistor has developed an open circuit — meaning the PCB is either receiving no signal at all, or a signal so far outside the expected range that it cannot calculate a reliable water temperature. The DHW thermistor is a small NTC (negative temperature coefficient) sensor; it doesn't report an actual temperature in degrees, it produces a resistance value in ohms that the PCB converts into a temperature reading. When that resistance reading disappears or goes wildly off scale, the boiler locks out rather than risk overheating or delivering scalding water. The result is that hot water stops working, though central heating may still function depending on model. The fault appears across several Vokèra ranges — on the Linea and Linea Max it is described as a secondary DHW thermistor fault, on the Syntesi it refers to the NTC sensor near the plate heat exchanger, and on Evolve models the display may read E060 instead.
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 or degraded DHW NTC thermistor Common
Over time the thermistor's internal resistance element deteriorates, particularly in hard-water areas where scale builds up around the sensor pocket. Once the element drifts outside acceptable limits or breaks entirely, the PCB registers an open circuit and locks the boiler out. This is the most frequent root cause of an 06 fault.
- Loose or corroded wiring connections Common
Boilers vibrate during every firing cycle, and over months or years the push-fit connectors on the DHW thermistor wiring can work loose at either end — at the sensor itself near the plate heat exchanger, or at the PCB. A partially detached connector produces the same open-circuit reading as a failed sensor. Corrosion on the terminals has the same effect. Engineers typically check this before condemning the sensor.
- Faulty PCB Sometimes
If the PCB's analogue input circuit for the DHW thermistor channel has failed — due to a power surge, component age, or moisture ingress — it will misread or lose the sensor signal entirely, triggering the 06 code even though the thermistor and wiring are both fine. A PCB fault is usually accompanied by other intermittent or unusual behaviour across the boiler.
How to fix it
- Reset the boiler (up to twice) DIY safe
Press and hold the reset button (labelled R on most Vokèra models) for around three to five seconds until the fault code stops flashing. On dial-style models, turn the selector to the reset or OFF/RESET position and hold briefly. If the boiler fires up and runs normally, monitor it over the next hour or two. An intermittent fault that clears on reset may indicate a loose connector rather than a dead sensor. Do not reset more than two or three times in quick succession — repeated failed resets will not fix a genuine component fault.
- Check your hot water taps while the boiler is running DIY safe
Open a hot tap and observe whether the boiler fires and produces hot water. If the 06 code returns within a short time, note whether it appears only when hot water is demanded or also at other times — this information will help the engineer narrow down the fault quickly.
- Have a Gas Safe engineer inspect the DHW thermistor wiring Gas Safe engineer
An engineer will access the boiler casing and trace the wiring from the DHW thermistor — located at the back of the heat exchanger assembly — back to the PCB. They will check each connector for security and corrosion, and use a multimeter to measure the resistance across the sensor at a known temperature. A healthy Vokèra NTC sensor typically reads around 10,000 ohms at 25 °C; a reading of infinity (open circuit) or near zero confirms a failed sensor.
- Replace the DHW NTC thermistor if confirmed faulty Gas Safe engineer
The engineer will drain the relevant circuit, remove the old sensor from its pocket in the heat exchanger assembly, and fit a replacement. Common compatible Vokèra part numbers include 10027352 (suitable for Compact, Linea, Syntesi, and Sabre ranges) and R8484 for the Syntesi. Genuine Vokèra parts are available from heating merchants, and compatible third-party sensors are also widely stocked. After fitting, the engineer will refill, check for leaks, and run the boiler through a hot-water cycle to confirm the fault has cleared.
- Test the PCB if the fault persists after sensor replacement Gas Safe engineer
If a new thermistor and verified wiring still produce an 06 code, the engineer will test the PCB's sensor input channels with a multimeter. They will confirm the board is receiving correct supply voltage and that all wiring harnesses are seated properly. An inconsistent or absent signal on a known-good sensor circuit points to PCB failure. PCB replacement is a significant cost, so a competent engineer will exhaust all other possibilities first.
- Call a Gas Safe registered engineer if you have not already done so Gas Safe engineer
All internal boiler work — removing casing, accessing components, replacing the thermistor, and certainly any PCB work — must be carried out by a Gas Safe registered engineer. You can verify a contractor's registration at gassaferegister.co.uk. Do not attempt to open the boiler yourself.
Parts you may need
- Vokèra DHW NTC thermistor / sensor (part 10027352 — Compact, Linea, Syntesi, Sabre) · from £12
- Vokèra NTC sensor R8484 (Syntesi / compatible models) · from £8
- Vokèra PCB (model-specific — confirm before ordering) · 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–£250, depending on the underlying cause.
Frequently asked questions
Can I fix Vokèra fault code 06 myself?
The only DIY step is a boiler reset, which you can attempt once or twice in case the fault was a transient signal glitch. Everything beyond that — removing the casing, checking wiring, testing or replacing the thermistor, or inspecting the PCB — must be done by a Gas Safe registered engineer. Working inside a gas appliance without registration is illegal in the UK and potentially dangerous.
How much does it cost to fix a Vokèra 06 fault?
If the DHW thermistor itself is the problem, most homeowners pay between £100 and £250 in total, covering the engineer's call-out, labour, and the relatively inexpensive sensor part. If the PCB turns out to be the root cause, costs rise considerably — a replacement Vokèra PCB typically costs £180 to £400 for the part alone, pushing the total repair into the £300–£500 range. An engineer will check the cheaper and more likely causes first before recommending a PCB replacement.
Why does my Vokèra show A06 instead of 06?
Vokèra revised its fault-code display format on newer models, adding a letter prefix to each code. A06 and 06 refer to exactly the same fault — an open circuit on the domestic hot water thermistor. On Evolve models the same fault may appear as E060. The diagnosis and repair procedure is identical regardless of how the code is displayed.
Will a Vokèra 06 fault affect my central heating as well as hot water?
In most cases the 06 fault primarily affects domestic hot water, since the faulty sensor is dedicated to the DHW circuit. However, on some Vokèra models the boiler locks out entirely when a sensor fault is detected, meaning both hot water and central heating stop working. If your heating is also off, that is consistent with a full lockout triggered by the 06 code rather than a separate heating fault.
How can I prevent the DHW thermistor from failing again?
Annual servicing by a Gas Safe engineer is the most effective preventive measure. During a service the engineer cleans components, checks all electrical connections, and can spot a sensor that is beginning to drift before it causes a full lockout. In hard-water areas, fitting a scale reducer or inhibitor to the system helps protect sensors and the heat exchanger from limescale build-up, which is a common cause of premature thermistor failure.