Vokera E094 Fault Code: Causes, Fixes & Repair Costs
What does the Vokera E094 fault code mean?
The E094 code appears on Vokera Evolve boilers and indicates a flame failure — the boiler attempted to ignite and sustain a burner flame, but the flame detection system either could not detect the flame or lost sight of it during operation. As a safety measure, the boiler shuts itself down into lockout mode. The 'E' prefix is specific to the Evolve range; other Vokera models use different formats such as 'A' codes (older models) or 'AL' codes (Mynute series), but the underlying safety logic is the same across the range. Until the root cause is identified and resolved, the boiler will continue to lock out after each attempted restart.
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
- Dirty flame sensing electrode Common
Even a thin layer of dust or carbon deposits on the flame sensing electrode can prevent it from detecting the burner flame reliably. This is consistently one of the most common triggers for E094 and is often resolved during a routine service clean.
- Incorrect electrode gap Common
The gap between the ignition and sensing electrodes must fall within the manufacturer's specified tolerance. If the gap has drifted slightly — due to wear, vibration, or a previous repair — flame detection becomes unreliable, particularly at lower burner loads.
- Combustion instability at low burner load Sometimes
E094 is sometimes triggered only when the boiler is firing at a reduced rate (modulating down). Poor gas-to-air mixture balance can cause the flame to become unstable or lift off the burner at low output, leading the sensor to lose signal.
- Gas supply or gas pressure issue Sometimes
Low gas pressure or an intermittent supply will prevent a stable flame from forming. If other gas appliances in the property are also affected, the issue may lie with the meter or the supply upstream of the boiler.
- Blocked or partially obstructed flue Sometimes
A flue that is blocked, incorrectly terminated, or allowing combustion gases to recirculate back into the air intake can disrupt the air-to-gas ratio and prevent proper combustion, causing the flame to fail.
- Faulty gas valve Sometimes
A gas valve that is sticking, not opening fully, or delivering gas at the wrong rate will prevent a stable flame. This is a less common cause but should be tested if electrode and combustion checks come back normal.
- Defective PCB Rare
If the PCB is misreading or failing to process the signal from the flame sensor, it may incorrectly conclude that no flame is present even when combustion is occurring normally. PCB faults are relatively rare and are usually diagnosed after other causes have been ruled out.
How to fix it
- Note down the fault code before doing anything else DIY safe
Take a photo of the boiler display or write down 'E094' and the time it appeared. This helps track whether the fault is recurring and gives a Gas Safe engineer useful context when they arrive.
- Check that the gas supply to the boiler is on DIY safe
Confirm the gas isolation valve on the supply pipe to the boiler is in the open position (handle in line with the pipe). Check whether other gas appliances such as a hob or gas fire are working normally. If no gas appliances are working, contact your gas supplier rather than resetting the boiler.
- Reset the boiler once DIY safe
Press and hold the reset button for 3 to 5 seconds until the fault code stops flashing, then release. Allow the boiler a full minute to attempt a restart. One reset after basic checks is reasonable. If the boiler locks out again with E094, do not keep resetting — repeated resets can mask a serious underlying fault and cause further damage.
- If the boiler locks out again, stop resetting and call a Gas Safe engineer Gas Safe engineer
A Gas Safe registered engineer will carry out the following checks that are not safe or legal for a homeowner to attempt: cleaning or replacing the flame sensing electrode; inspecting and adjusting the electrode gap to manufacturer specification; testing gas valve operation and supply pressure; checking flue integrity and terminal condition for obstructions or recirculation; testing PCB flame detection circuitry and replacing the board if it is misreading sensor signals.
Parts you may need
- Flame sensing electrode · from £35
- Ignition electrode · from £30
- Gas valve · from £120
- PCB (printed circuit board) · 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 £150–£350, depending on the underlying cause.
Frequently asked questions
Can I fix the Vokera E094 fault myself?
The only steps a homeowner can safely take are checking the gas supply is on and attempting a single boiler reset. Everything beyond that — cleaning or replacing the flame sensing electrode, adjusting the electrode gap, testing the gas valve, or inspecting combustion — must be carried out by a Gas Safe registered engineer. Attempting gas-related work without the correct registration is illegal in the UK and potentially dangerous.
Why does my Vokera Evolve keep showing E094 even after a service?
Some Vokera Evolve units are known to have particularly sensitive flame detection sensors. If E094 reappears after a service, ask your engineer to specifically check the electrode gap and combustion stability at low burner load, as the fault sometimes only triggers when the boiler is modulating down to a low firing rate. Adjusting the electrode gap to the lower end of the manufacturer's tolerance can make a noticeable difference in these cases.
How much does it cost to repair a Vokera E094 fault?
Most people with this fault pay between £150 and £350 all in, which typically covers the engineer's call-out, diagnosis, and either an electrode clean or replacement. If the gas valve needs replacing, costs can reach the higher end of that range. A PCB replacement is a less common outcome but can add significantly more — potentially £300 to £500 for the part and labour — and is worth weighing against the age and condition of the boiler.
How long do boiler flame sensing electrodes last?
On a well-maintained boiler with annual servicing, electrodes typically last around three to five years. High-usage boilers or those that have gone several years without a service may need electrode attention sooner. Keeping up with annual servicing is the most reliable way to catch electrode wear before it causes a lockout fault like E094.