Vaillant F.62 fault codewhat it means and how to fix it
The gas valve is not shutting off when the boiler tells it to. This is a gas safety fault and the boiler must not be used until an engineer has seen it.
Stop — this needs an engineer
Get a Gas Safe registered engineer to look at your Vaillant F.62
Gas Safe Register engineers only. No obligation.
What F.62 means
F.62 means the control board commanded the gas valve to close and did not see it close within the expected time. The board monitors this every cycle, because a gas valve that closes slowly or not at all is the single most serious failure mode a domestic boiler has. It means gas can continue to flow after the burner should have stopped. The boiler locks out and refuses to operate, and that lockout should be left in place. There is nothing a householder can check here. Do not reset it more than once, and if it returns, turn the appliance off and leave it off until it has been repaired.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| Faulty gas valve | The valve mechanism is slow to close or is not closing fully. Replacement is the only remedy and it is a gas-qualified job. | Common |
| Control board fault | The board is commanding correctly but misreading the valve feedback, or is failing to send the shut-off signal at all. | Occasional |
| Damaged wiring to the gas valve | A chafed or corroded connection between the board and the valve. Found by inspection during diagnosis. | Rare |
Can you fix it yourself?
Stop — this needs an engineer
What it costs to fix
Typical repair cost
£280–£450
Time on site
2 hours
Gas valve replacement £280–£450 including the mandatory combustion check afterwards. Control board, if that is the cause, £320–£520.
Typical UK prices including parts and labour, updated August 2026. Your quote may differ.
Parts you may need
We may earn a commission if you buy a part through one of these links. It does not change what you pay, and it does not affect which parts we list.
Vaillant ecoTEC gas valve
0020053968£110–£210Authorised Vaillant parts distributor
Price checked 5 August 2026
What other owners found
Nobody has shared what worked for them on this code yet. If you have had it, you would be the first — and it genuinely helps the next person.
Related Vaillant fault codes
- F.28Stop — call an engineerThe boiler tried to light and failed three times in a row, so it has shut the gas off and locked out. Do not keep resetting it.Related: ignition and gas supply
- F.29Stop — call an engineerThe boiler lit correctly and then lost the flame while it was running. It has shut the gas off and locked out, and it needs an engineer.Related: ignition and gas supply
- F.61Get it checkedThe gas valve control circuit has faulted. The boiler will not fire and this is firmly an engineer's job.Related: ignition and gas supply
- F.27Stop — call an engineerThe boiler is detecting a flame when the burner should be off. Switch it off and get a Gas Safe engineer out rather than resetting it.Related: ignition and gas supply
- F.54Get it checkedA gas supply fault, usually shown alongside F.28 or F.29. It means gas is reaching the appliance at too low a pressure.Related: ignition and gas supply
- EA 227Stop — call an engineerThe boiler tried to light and never detected a flame, so it has shut the gas off and locked out. This is the most common Worcester fault code.Related: ignition and gas supply
Related guides
Common questions about Vaillant F.62
Can I use the boiler until the engineer arrives?
No. Turn it off at the front panel and leave it off. This code specifically indicates that the component responsible for stopping the gas is not behaving as it should, and that is not a fault to work around for a few days.
Should I turn the gas off at the meter?
If you can do so easily and you are not leaving other essential appliances without gas, it is a reasonable precaution. If you can smell gas at any point, leave the property and call 0800 111 999 rather than investigating.
How much does a gas valve cost to replace?
Typically £280 to £450 fitted on a Vaillant ecoTEC, including the combustion analysis that must follow. On a boiler over twelve years old it is worth asking whether that money is better put toward replacement.
Sources and how we verified this
We establish the facts from the sources below and then write the explanation ourselves. We do not copy manufacturer wording and we do not host their manuals.
- Manufacturer technical and service documentation
- Trade body guidance
Checked by Technical reviewer (Gas Safe registration to be displayed on appointment) on 5 August 2026.