Vokera E095 Fault Code: Causes, Fixes & Repair Costs
What does the Vokera E095 fault code mean?
The E095 code appears on Vokera boilers when the boiler's internal monitoring detects abnormal combustion conditions — specifically that carbon monoxide or exhaust gases are being produced at unsafe levels. As a safety measure, the boiler restricts the ignition cycle and enters a temporary lockout, running the fan at maximum speed for around five minutes to purge the combustion chamber before allowing a reset attempt. Because this fault is directly linked to CO production, it should be treated as a serious issue and not simply reset and ignored.
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 or scaled primary heat exchanger Common
Scale, sludge, or debris build-up on the heat exchanger reduces its ability to transfer heat efficiently from the burner to the heating water. This disrupts the combustion process and causes CO levels to rise, directly triggering E095. It is the single most common root cause, particularly on boilers that have not been serviced regularly.
- Flue blockage or restriction Common
If the flue terminal is obstructed — by a bird's nest, debris, or ice in winter — exhaust gases cannot escape properly. CO and combustion products back up inside the heat exchanger, causing the boiler's sensors to detect elevated levels and raise E095.
- Fan fault or worn fan bearings Common
The combustion fan controls the air-to-gas ratio by managing airflow through the burner. If the fan is running too slowly, has worn bearings, or has failed, the combustion mixture becomes imbalanced, producing excess CO. Vokera fans are noted for bearing wear over time.
- Boiler not serviced for an extended period Common
A boiler running for several years without a service will accumulate scale on the heat exchanger, have a partially fouled burner, and may have components that have drifted out of specification. The cumulative effect can push CO production above safe limits even if no single component has failed outright.
- Gas valve drift or incorrect combustion calibration Sometimes
If the gas valve has drifted out of calibration, the gas-to-air ratio at the burner will be incorrect. Too much gas relative to air produces incomplete combustion and elevated CO. This requires a flue gas analyser to confirm and a Gas Safe engineer to adjust.
- Cracked heat exchanger or failed flue seal Rare
Physical damage to the heat exchanger or a deteriorated flue seal can allow combustion gases to leak into the boiler casing rather than being expelled correctly. This is a less common but serious cause that must be ruled out by an engineer.
How to fix it
- Turn off the boiler and ventilate the area DIY safe
If you have any concern that CO is present — headaches, dizziness, or a CO alarm sounding — leave the property immediately and call the Gas Emergency Service on 0800 111 999. If there are no such symptoms, turn the boiler off at the programmer or thermostat and open a window near the boiler to allow fresh air in while you carry out initial checks.
- Wait for the post-purge cycle to complete, then attempt a single reset DIY safe
After E095 triggers, the Vokera boiler runs the fan at maximum speed for approximately five minutes to clear the combustion chamber. Once this cycle finishes, press and hold the reset button (labelled R on most models) for 3–5 seconds, or turn the selector dial to the reset/off position on dial-control models and hold briefly. If the boiler restarts and runs normally, monitor it closely. Limit resets to no more than two or three attempts — repeated resets without addressing the underlying cause are unsafe and will not resolve a genuine combustion problem.
- Check the flue terminal externally for obvious blockages DIY safe
From outside your property, visually inspect the flue outlet (the white or grey pipe exiting through the wall or roof). Check for visible obstructions such as leaves, debris, or a bird's nest around the terminal. Do not attempt to reach inside the flue or dismantle any pipework — simply note what you can see and report it to your engineer. Do not restart the boiler if a blockage is visible.
- Call a Gas Safe registered engineer promptly Gas Safe engineer
Because E095 is a combustion and CO-related fault, a Gas Safe registered engineer must attend to carry out a full investigation. They will use a calibrated flue gas analyser to measure CO and CO₂ levels, inspect and clean the primary heat exchanger, check the fan for correct speed and bearing condition, verify the flue is clear and correctly installed, and test the gas valve calibration and burner settings. You can verify any engineer's credentials at gassaferegister.co.uk. Do not continue running the boiler until it has been properly assessed.
Parts you may need
- Combustion fan / flue fan assembly · from £120
- Primary heat exchanger · from £280
- Gas valve · from £150
- Flue gas thermostat / flue thermistor · from £35
- PCB (printed circuit board) · from £320
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
Is the Vokera E095 code dangerous?
Yes, this fault should be taken seriously. E095 indicates that the boiler has detected abnormal combustion conditions and potentially elevated carbon monoxide output. CO is an odourless, colourless gas that is harmful at elevated concentrations. The boiler locks itself out as a safety precaution. Do not repeatedly reset and run the boiler without having a Gas Safe engineer investigate the root cause. If you have a CO alarm sounding or anyone in the property feels unwell, leave immediately and call the Gas Emergency Service on 0800 111 999.
Can I fix Vokera E095 myself?
A homeowner can safely attempt one or two resets after the boiler's fan purge cycle completes, and can check the external flue terminal for obvious blockages. Beyond that, this fault requires a Gas Safe registered engineer. Combustion analysis, heat exchanger cleaning, fan replacement, and gas valve adjustment all involve gas components that are legally required to be worked on only by a Gas Safe registered professional.
How much will it cost to fix Vokera E095?
Most people with this fault pay between £120 and £350 all-in, covering the engineer's callout, diagnosis, and the most common repairs such as a heat exchanger clean or fan replacement. If the gas valve needs replacing, expect to add around £150–£200 for the part. In rare cases where the PCB is implicated or the heat exchanger is cracked and needs replacing, costs can rise significantly — a new PCB alone can cost around £300–£500, at which point it may be worth considering a full boiler replacement, particularly on older Vokera models.
Why does E095 keep coming back after I reset it?
A reset only clears the fault code from the display — it does not fix the underlying problem. If E095 returns shortly after a reset, it means the combustion fault is still present. Common culprits are a fouled heat exchanger, a fan running below the correct speed, or a miscalibrated gas valve. Each reset and restart cycle without a proper repair carries a safety risk. Book a Gas Safe engineer as soon as possible rather than continuing to reset the boiler.
Will my Vokera warranty cover E095?
It may do, depending on the age of your boiler and whether annual servicing has been carried out by a Gas Safe registered engineer as required by Vokera's warranty terms. Check your warranty documentation and contact Vokera directly. If your boiler is out of warranty, Vokera does offer a fixed-price repair option that covers callout, labour, and parts, which can give you cost certainty for this type of fault.