Viessmann boilers, such as the Vitodens range, show a fault code on the display when they stop. Viessmann uses many different control units, and the same code can mean different things on different models — so this guide covers only the common codes, and your user manual is always the final word.
📊 Common Viessmann Fault Codes
| Code | What it means | What to do |
|---|---|---|
| F4 | No flame, or the flame signal isn’t detected | ✅ Check gas supply and condensate pipe, reset once |
| F2 | Overheat — the temperature limiter has tripped | ✅ Check pressure, reset once, then call an engineer |
| F9, 58 | Burner in fault mode | Reset once, then call an engineer |
Any other code? Look it up in your user manual, or call us with the code and the model name on the front of the boiler.
🔥 F4 — No Flame
- Do your other gas appliances, such as the hob, work? If not, the problem is the gas supply, not the boiler.
- On a prepayment meter? Check it has credit, and check the boiler has power.
- Freezing outside? A frozen condensate pipe can cause F4 on some Vitodens boilers. Warm the outside plastic pipe with a hot water bottle or warm (never boiling) water, only where you can reach safely from the ground.
- Then reset once.
If F4 comes back, stop resetting and call a Gas Safe engineer.
🌡️ F2 — Overheating
The boiler got too hot and a safety device has stopped the burner. It usually means water isn’t circulating properly — low pressure, air in the system, closed radiator valves or a pump problem. Check the pressure gauge reads about 1–1.5 bar and that radiator valves are open, then reset once. If F2 returns, it needs an engineer.
💧 Low Pressure and Resetting
Most Viessmann boilers run at 1–1.5 bar. If the gauge is lower, top up with the filling loop as shown in your user manual. If the pressure keeps dropping, there’s a leak and it needs an engineer — see boiler pressure low.
To reset, use the reset button on the boiler’s control panel. How long to hold it differs between models, so follow your user manual. Reset once after doing the checks; if the same code keeps coming back, resetting won’t fix it.
💷 Viessmann Repair Costs in London
| Repair | Rough price |
|---|---|
| Low pressure or condensate fix | £80 – £150 |
| Sensor, thermostat or ignition part | £100 – £250 |
| Diverter valve, fan or pump | £150 – £350 |
| Gas valve or circuit board (PCB) | £200 – £550 |
| Heat exchanger | £300 – £700 |
Rough guide for London, parts and labour. The exact price depends on your boiler and the part. Our engineer gives you a fixed price after seeing the boiler, before any work starts. No VAT added.
Boiler still under its Viessmann guarantee? Contact Viessmann first, as they deal with guarantee repairs. Old boiler that keeps breaking down? See repair or replace your boiler.
🏆 Viessmann Repairs with FE Maintenance
- Gas Safe registered, fully insured — every engineer works directly for FE Maintenance, no subcontractors
- Fixed price agreed before any work starts, no VAT added
- Emergency call-outs Monday to Friday, 8am–8pm, from £99 — see emergency gas engineer
- Yearly boiler service from £80 to catch faults early
We cover North, West and Central London, plus Potters Bar and Hatfield. Call 020 8445 1303 or ask for a quote.
General guidance, cross-checked against several published Viessmann fault code lists, as of October 2026. Viessmann codes vary a lot between models and control units — your boiler’s user manual is the final word.
Frequently Asked Questions
Viessmann Still Showing a Fault?
A Gas Safe engineer from FE Maintenance can find the cause and fix it, with a fixed price agreed before any work starts.
info@femaintenance.com · 171 Crescent Road, Barnet EN4 9RN