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Common Vokera Boiler Problems


Vokera Limited is one of the top heating manufacturer in the UK. It was started more than 35 years ago and is based in Ireland and the UK. The company offers a complete heating package and tests everything before it leaves their hands. Also, they are one of the most affordable heating options available.

But given that they are budget boilers, they are generally made from cheaper materials as well. As such, it’s no surprise that your boiler has failed to heat water, has blanked out, is overheating or making strange noises.

Luckily, Vokera has some common fault codes and quick fixes you can try as explained below.

Faulty Fan: A03 error code

This error code is common with the Vokera Compact boilers. It shows that the boiler has a fan fault. Quality fans often outlast most boilers. But since Vokera often uses cheaper components, the fan is most likely to breakdown before the boiler outlasts its warranty.


The Gas Safe engineer has to diagnose the problem with the boiler fan in most cases, the fan doesn’t need replacement. One of the most common fan errors is worn out bearings. The engineer can purchase spare kits from local heating spare kit supplier at an affordable price.

However, it’s crucial that the engineer inspects the fan’s situations and confirms that there won’t be another fan problem soon after the repair. If the assessments show there will be, it’s economical to replace the fan instead.

If the fan is intact, it could be a wiring issue. With a multi-meter, an engineer will check the wiring to see where there’s a voltage drop.

Low Boiler Pressure: Error code 41, 40 or A04

These error codes are common on the Vokera Compact and Vokera Linea boilers. Also, low boiler pressure is common in other boiler brands as well.

Low boiler pressure or boiler losing pressure will not function properly. Low boiler pressure is normal but it could also signify a leak in the boiler system.


Usually, topping up the boiler with water through the external filling loop will help clear the error code. But if the error code doesn’t disappear, it means there’s a leak in the system.

Identifying a leak is not easy especially because it could be anywhere externally and within the system including:

  • The boiler pump
  • Radiator, radiator valves and towel rails
  • Expansion vessel
  • Gate valves and stop taps
  • Boiler auto air vent

Inspect the above components for leaks. As you inspect them, tighten them as well (it might help fix the problem). When you find the leak, repair or replace the component as soon as you can.

Water is not getting hot

The water could either not be getting hot or only gets lukewarm when the heating is set to the highest temperature.

The common cause of this boiler problem is a faulty diverter valve. Unfortunately, the diverter valve especially those on the Unica HE and Flowmatic are of low quality and fail often. Diverter valves are important since they switch between heating and hot water. When you turn on a shower or tap, the diverter opens and focuses on the hot water and when the tap/shower s closed, it flips back to focus on heating.

If your boiler is not providing hot water, it’s possible the diverter valve is stuck.


In most situations, the entire diverter doesn’t need replacing since the problem is usually the washers. However, the cost of labour to take the diverter valve apart is high. As such, Gas Safe engineers recommend replacing the entire unit instead.

Diverter valve diverter replacement is cheaper than it is on other brands. £250 is enough to cover the repair costs. On the flip side, if your boiler is out of warranty, it best to consider boiler replacement.

Failure to Ignite: Error code 10 or A01

The error code 10 in the Vokera Linea and the A01 error code on the Vokera Compact represent the same problem. The fault signals a problem with boiler ignition. The problem is caused by several factors including faulty ignition leads or gas valves.

But in most cases, it’s usually a problem with the PCB. The PCB requires £500 to replace. If your boiler is old you shouldn’t invest that much. After all, it will develop fresh problems soon. If the PCB needs to be replaced, first consider replacing your Vokera boiler.


Hire a Gas Safe engineer to determine if it’s a problem with the PCB, ignition leads or gas valves. They will pinpoint the problem through circuit testing and later advise on the best fix.

Frozen Condensate Pipe: Error codes 92, 95 or 93

These error codes are displayed by Vokera Linea boilers. They represent blocked condensate pipes a problem that all boilers will experience at some point. The blockage might be in the pipe directing waste into the drainage system or the trap.


When it’s cold, confirm the condensate pipe is not frozen. Usually, debris builds up and moisture collects in the pipe. When the temperature drops below zero degrees Celsius, the moisture and debris freeze and cause a blockage in the pipe.

Thaw the plastic pipe with warm water and remove the debris. However, if it’s not cold but the pipe is blocked, it’s just debris built up. Removing the pipe and cleaning it will unblock it. if not, buy a new condensate pipe.

Boiler Needs Service: Error code _CL

Your boiler should be serviced annually by a registered Gas Safe engineer. The servicing can be done within 24 hours. The service should cost anything between £70 and £100. The actual price depends on whether you higher an international company o an independent Gas Safe engineer. Most companies charge £110+ for boiler servicing.


The Gas safe engineer will test that the boiler is running efficiently and safely. They will test flue gases and flush the system. They will also install magnetic filters to trap debris and prevent future boiler blocks.

Faulty Hot Water Sensor: Error code A06

Vokera boilers have multiple thermistors. They measure boiler resistance in ohms and send feedback to the PCB. Basically, they keep the PCB updated on heating and water temperatures.

When water reaches set temperatures, the PCB turns off gas supply otherwise the burner remains operational. Faulty How Water Sensors is often caused by:

  • Loose or damaged wiring or connections
  • Faulty PCB


If it’s a faulty PCB, the Gas Safe engineer will replace the PCB and if it’s damaged or loose wiring, they should be re-secured or replaced. If the PCB is the problem and the boiler is old and out of warranty, it’s a better idea to install a new boiler.

Faulty NTC Thermistor: Error code A07

The NTC thermistor monitors the hot water leaving and returning to the boiler. There’s usually a normal temperature differential between these two flows (the flow pipe is hotter than the return pipe). If the differential is exceeded, the boiler displays the error code A07 and locks out.

The common cause of this problem is a fault in the circulation including:

  • Faulty pumps
  • Incorrect pump installation
  • Boiler pump airlock
  • Heating sludge build-up

In some other cases, it’s simply a faulty NTC thermistor.


If it’s a faulty boiler pump, the Gas Safe engineer will repair or replace it. But if it’s a block, they’ll introduce a scale reducer or a limescale inhibitor to combat the problem.

If the thermistor is the problem, replacing it will clear the A07 error code.

Faulty NTC Thermistor: Error code A08

Like the A07, the A08 error codes point to a faulty NTC thermistor and a differential issue. But in this case, the return pipe is hotter than the flow pipe. Since the flow on the boiler comes from the heat exchanger, it should be hotter than the return flow.

A common cause is a faulty thermistor or incorrectly installed thermistors (the latter only happens on newly installed boilers. It could also be a faulty PCB.


Replace the faulty NTC thermistor. They cost less than £30. Again, if it’s a PCB issue, consider installing a new boiler if it’s out of warranty.

False Flame: Error code A11

A false flame is a situation in which the Vokera boiler still has a flame even when there’s no demand for hot water or heating. The most common cause of this problem is a stuck gas valve.

And since the gas valve is controlled by the PCB, the fault could also denote a faulty PCB. On the other hand, it could be a faulty flame sensor.


Once you receive this error code, don’t reset the boiler. Resetting the boiler might get the boiler running but it doesn’t fix the fault.

If it’s a faulty flame sensor or gas valve, replacement is affordable. New gas valves cost anywhere between £250 and £300. PCB replacements on the other hand cost about £550 and need around 24 hours to install.

Other fault codes and troubleshooting

Fault code A02 – Limit thermostat fault.

How to fix – Replace thermostat batteries and reset the boiler.

Fault code A09 – Flue thermistor fault.

How to fix – Check wiring and inspect flue thermistor. Fix the wiring or replace the thermistor and reset the boiler.

Fault code A77 – Low-temperature thermostat fault.

How to fix – Inspect low-temperature thermostat and replace.

Fault code ACO – Service operation.

How to fix – No fix.

How to Improve Your Boiler’s Life

Vokera boiler warranty

Most Vokera boilers come with a 5-year warranty. However, some models including Vokera Evolve have 10-year warranties. These warranties are dependent on meeting some terms and conditions.

First, once an installation is done, you have 30 days to register and claim your Vokera boiler warranty. Additionally, to sustain your warranty, annual boiler service is required. Proof of annual service is needed to ascertain the service was done by a Gas Safe engineer.

Vokera boiler cover

If the Vokera boiler has expired getting a boiler cover/insurance is a feasible option. You can take a cover with your current energy supplier but it’s not a must. When are comparing boiler covers, get one with the best annual service as well as safety inspection.

Vokera boiler service

Vokera will hire an experienced and professional engineer to conduct the service as follows:

  • Inspect the performance of the boiler, ventilation and flue.
  • Visually inspect the boiler for leaks.
  • Inspect the boiler for worn out and damage components.
  • Inspect and clean the heat exchanger and burner.
  • Check for flame failure.
  • Conduct a flue gas combustion analysis.

The most common faults on your Vokera boiler are easy and inexpensive to fix. However, some faults like a faulty/broke PCB are too expensive and cost as much as £500. In such cases, installing a new boiler makes economic sense since it will save you up to £300 annually on energy bills.

We can provide you with 3 new boiler quotations from reputable brands and Gas Safe engineers to get you started on a new boiler installation.

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