Vokera Boiler Problems: Fault Codes, Causes and What to Check

The most common Vokera boiler problems are failure to light, low water pressure, overheating, fan or flue faults, and hot water or heating failing on its own. What makes Vokera confusing is that different ranges show the same fault in different ways: an A code on some models, a plain number on others, an AL code on the Mynute and an E code on the Evolve. Find your model name first, then read the code.

Why Vokera Fault Codes Look Different Between Models

Vokera has used several control systems over the years, so the same fault can appear as A01 on one boiler and 01 on another. The model name tells you which list to use.

The model is usually printed on the front of the boiler or on the data badge underneath: Compact, Unica, Vision, Linea, Mynute, Evolve and Easi-Heat are the common ones in London homes. As a rough guide:

• A codes (A01, A02, A04 and so on) appear on many Compact, Unica and Vision boilers.
• Plain numeric codes (01, 02, 03, 04) appear on some other displays for the same basic faults.
• AL codes (AL10, AL40 and so on) are used on Mynute models.
• E codes are used on the Evolve range.

Because the lists differ, treat any code table as a guide and confirm the meaning in the manual for your exact model before acting on it.

The Common Vokera Codes and What They Mean

Across the A code and numeric lists, the first few codes cover the faults we are asked about most. These are the widely published meanings:

• A01 or 01: ignition failure. The boiler tried to light and did not detect a flame.
• A02 or 02: overheat. The limit thermostat has tripped because the boiler got too hot.
• A03 or 03: fan or flue fault. The fan is not working as expected, or the boiler cannot confirm the flue gases are clearing.
• A04 or 04: insufficient water pressure. System pressure has dropped too low for the boiler to run.
• A06: hot water thermistor fault. The sensor that measures hot water temperature has failed or lost contact.
• A07 and A08: flow or return temperature problems, usually pointing to a thermistor or to poor circulation.
• A09: flue thermistor fault on models that monitor flue temperature.

If your code is not on this list, or your boiler shows an AL or E code, check the manual. If you are unsure, note the full code and model and give both to the engineer.

Low Pressure on a Vokera: A04 or 04

A04 is the code most Vokera owners can deal with themselves. It means the pressure in the heating system has fallen too far, usually below about 1 bar on the gauge.

Top the system up to about 1 to 1.5 bar through the filling loop, following the manual, then reset. Our guide to repressurising a boiler safely covers the steps. If the code returns within days or weeks, the problem is not the pressure but the reason it keeps dropping: a leak on a radiator or pipe, a pressure relief valve letting by, or an expansion vessel that has lost its charge. Our guide to why a boiler keeps losing pressure explains how to tell them apart.

Ignition Failure: A01 or 01 and a Flashing Red Light

A01 means the boiler attempted to light and failed, and on many Vokera models it comes with a flashing red light. It is the most common lockout on the brand.

Check what you safely can: that other gas appliances work, that a prepayment meter has credit, and that the gas valve under the boiler is open. In freezing weather check the condensate pipe outside, because a frozen pipe stops condensing boilers from lighting. Our guide on a frozen condensate pipe covers how to thaw it without boiling water. Beyond that, the causes are inside the boiler: the ignition electrode, the flame sensing circuit, the gas valve, the fan or the control board. Those are for a Gas Safe registered engineer, by law.

How to Reset a Vokera Boiler

Most Vokera boilers reset by turning the mode selector to the off or reset position for a few seconds, then back to hot water only or heating and hot water. Some newer models have a dedicated reset button instead.

Reset once, after you have checked pressure, gas and the condensate pipe. If the boiler lights and runs normally, keep an eye on it. If the same code comes back, stop resetting. A lockout that keeps returning has a cause that a reset cannot clear, and repeated attempts to light against an ignition or overheat fault put extra strain on parts that are cheaper to fix early.

Other Vokera Problems: Hot Water, Noise and Condensate

Not every Vokera problem shows a code. Lukewarm or up-and-down hot water, banging or kettling noises and a boiler that gurgles and then locks out each point to a different part.

On a Vokera combi, hot water that is weak or swings between hot and cold usually points to scale on the plate heat exchanger or a sticking diverter valve, and London's hard water makes scale common. Banging or kettling means water is boiling in pockets inside a heat exchanger narrowed by sludge or scale, often with a weak pump. Gurgling followed by a lockout in cold weather is the classic sign of a blocked or frozen condensate trap or pipe. If the heating works but there is no hot water at all, the diverter valve and the flow sensor are the first parts an engineer will test.

Is a Vokera Boiler Worth Repairing?

Usually, if the fault is a single part such as an electrode, sensor, fan, pump or diverter valve. It is a closer call on an older boiler where the main heat exchanger is failing or faults keep stacking up.

Ask the engineer what failed, why it failed and whether the cause, such as sludge, will damage the new part too. That answer matters more than the part price. We repair Vokera boilers across London. You can book a Vokera boiler repair, and it helps to have the model name and full fault code ready when you call.