In This Guide
What does the Vaillant F62 error code mean?
F62 is a gas valve shut-off fault. Your Vaillant boiler constantly checks that the gas valve opens and closes exactly when it should. When the boiler detects that the valve is not shutting off within the expected time, or that the signal controlling it is wrong, it locks out and displays F62 rather than risk running with a gas valve it cannot rely on. It is most common on Vaillant ecoTEC models.
Because the fault sits on the gas side of the boiler, F62 is treated as a safety lockout. The boiler is doing the right thing by stopping, and the fault needs diagnosing at the gas valve and the control board rather than cleared and ignored.
What Causes a Vaillant F62 Fault?
There are four common causes, and they are best separated by a Gas Safe engineer because the symptoms overlap:
Cause | What happens | Typical fix |
Faulty or sticking gas valve | The valve does not shut off cleanly, so the boiler locks out for safety | Gas valve repair or replacement by a Gas Safe engineer |
Defective PCB (control board) | The board misreads or mismanages the gas valve signal | PCB diagnosis and replacement |
Wiring or connection fault | A poor connection between the PCB and gas valve triggers the fault | Inspection and repair of the wiring |
Wear over time | Older boilers develop gas valve wear | Component replacement, or honest repair-vs-replace advice |
F62 sometimes appears alongside other codes. If it shows with a flame or ignition code, the gas supply to the burner is worth checking as part of the same visit. Our guide to the Vaillant F29 flame failure fault covers that side, and where the control board is suspected, the Vaillant F65 electronics fault explains the PCB-related failures that can also affect the gas valve circuit.
Can you fix a Vaillant F62 fault yourself?
Only up to a point, and safely so. You can turn the boiler off and on once to clear the code, in case it was a one-off glitch. If F62 returns, stop there. The gas valve, the PCB, and the gas-carrying components are not DIY territory, and it is illegal for anyone who is not Gas Safe registered to work on them. Repeatedly resetting a boiler that keeps locking out on F62 will not fix the cause and can mask a genuine gas fault.
If the code comes straight back, or if you notice any smell of gas, turn the boiler off and call a Gas Safe engineer. If you suspect a gas leak, leave the property and call the National Gas Emergency Service on 0800 111 999.
Getting a Vaillant F62 fault repaired
0800 Homefix are Gas Safe registered engineers covering London and the South East, and gas valve faults like F62 are routine work for us. An engineer will confirm whether the gas valve, the PCB, or the wiring is at fault before recommending anything, so you are not paying to replace parts on a guess. You can see the full service on our Gas Safe boiler repair page, and regular Vaillant boiler servicing is the best way to catch gas valve wear before it locks the boiler out.
On cost, 0800 Homefix charges boiler repair as the first hour of labour, paid in advance, with any parts or further work quoted and agreed with you before we proceed. For current rates, see our rates page. Our labour is guaranteed for 12 months, and any parts we fit are covered by the manufacturer’s 12-month guarantee.
Frequently Asked Questions
What does the Vaillant F62 code mean?
It is a gas valve shut-off fault. The boiler has detected that the gas valve is not closing when it should, or that the signal controlling it is faulty, and has locked out for safety.
Can I fix a Vaillant F62 fault myself?
You can reset the boiler once to rule out a glitch. Beyond that, no. F62 involves the gas valve and control board, which by law must be worked on by a Gas Safe registered engineer.
Is a Vaillant F62 fault dangerous?
The lockout itself is the boiler protecting you by refusing to run with a gas valve it cannot trust. The underlying fault should be repaired promptly by a Gas Safe engineer. If you ever smell gas, leave the property and call the National Gas Emergency Service on 0800 111 999.
Will resetting the boiler clear F62?
A reset may clear the display briefly, but if the gas valve, PCB, or wiring is at fault the code will return. Repeated resets do not fix the cause and can hide a genuine gas fault.
How is a Vaillant F62 fault repaired?
A Gas Safe engineer diagnoses whether the gas valve, the control board, or the wiring is responsible, then repairs or replaces the faulty component and confirms the boiler is running safely before leaving.
Helpful Resources
- Gas Safe Register: check an engineer is registered to work on your boiler.
- Vaillant UK: official manufacturer support and fault-code information.
Spotted Any of These Warning Signs?
Seeing an F62 fault on your Vaillant boiler? 0800 Homefix has Gas Safe registered engineers across London and the South East who can diagnose the gas valve, board, and wiring and get your heating back safely, seven days a week, 365 days a year.
Editorial note: This article is intended as a general homeowner guide. All plumbing work on supply pipes should be carried out by a qualified, WaterSafe-registered plumber. If you suspect a gas leak, leave the property immediately and call the National Gas Emergency Service on 0800 111 999.
