Boiler
E07
The E07 error code on a Viessmann boiler indicates a fault with the ignition or flame detection — the boiler is failing to light or cannot confirm a stable flame. This is a moderately serious fault that will lock your boiler out and leave you without heating or hot water until it’s resolved.
What does this error mean?
E07 signals that your Viessmann boiler has attempted to ignite but either failed to establish a flame or lost the flame signal shortly after lighting. The boiler’s control board monitors combustion via an ionisation probe (flame sensor); if it doesn’t detect a flame within a set number of attempts, it triggers E07 and locks out as a safety measure. This lockout is intentional — it prevents unburned gas from building up inside your home.
Est. repair cost
£100–£250 for professional repair (parts + labour); no safe DIY repair option for this fault
🔍 Likely causes
🛠️ Step-by-step fix
Check your gas supply first: make sure other gas appliances (hob, gas fire) are working. If not, contact your gas supplier immediately — do not attempt to reset the boiler.
Check your prepayment meter has credit, or that your gas isolation valve (usually a lever near the meter or boiler) is fully open (lever inline with the pipe = open).
Perform a boiler reset: locate the reset button on your Viessmann boiler (typically a flame symbol on the display or a dedicated button), press and hold for 3–5 seconds as described in your manual, then wait 5 minutes for it to attempt a restart.
If the boiler resets but E07 returns within a few hours, do not keep resetting repeatedly — more than 2–3 resets without success means there is an underlying fault requiring professional diagnosis.
Do not attempt to inspect, clean, or replace the ignition electrode, ionisation probe, gas valve, or burner yourself — these components are inside the gas section of the boiler and must only be worked on by a Gas Safe registered engineer.
📞 When to call a professional
If E07 returns after a reset, or if you have confirmed your gas supply is fine and the boiler still won’t fire, call a Gas Safe registered engineer — this is not a DIY repair. Tell them your boiler model (e.g. Viessmann Vitodens 100-W), that you are seeing error code E07, and how many reset attempts you’ve made. A qualified engineer will test the ionisation probe, ignition electrode, gas valve, and flue to pinpoint the exact cause.
⚖️ Repair or replace?
Most E07 repairs — replacing an ionisation probe or ignition electrode — cost between £100 and £250 including parts and labour, making repair worthwhile on boilers under 10 years old. If your Viessmann boiler is over 10–12 years old and this is one of several recent faults, a new boiler installation (typically £2,000–£3,500 fitted in the UK) may be more cost-effective long-term. Viessmann boilers are generally regarded as high quality, so a well-maintained unit under a decade old is almost always worth repairing.