Viessmann Boiler Fault Codes | Wokingham Local Expert
If your Viessmann boiler is showing a fault code or has suddenly stopped heating your home, don’t panic. Many Viessmann boiler issues are easy to diagnose — and in some cases, simple to fix yourself.
This quick guide is designed for homeowners in Wokingham, Earley, Woodley, Winnersh, and surrounding areas. At Thermo-Tec Plumbing and Heating, our Gas Safe registered engineers are on hand to provide fast, expert support when you need it most.
Most Common Viessmann Boiler Fault Codes
Here’s what those Viessmann boiler fault codes mean — and how to troubleshoot or know when to call a professional.
F2 – Flame Signal Fault
Cause: Your Viessmann boiler failed to detect a flame during ignition. This can be caused by:
A faulty ignition electrode
Blocked or frozen condensate pipe
Gas supply interruptions
Fix:
Check for gas supply to other appliances
If it’s been cold, check the condensate pipe for freezing
Press the reset button once
If the code returns, book a service call. It could indicate a more serious issue with the ignition system or PCB.
F4 – Overheat / Safety Temperature Limiter Triggered
Cause: The boiler has exceeded its safe operating temperature. Common causes in Viessmann models:
Air in the system
Pump failure or restriction
Sludge build-up in heat exchanger
Fix:
Try bleeding radiators
Check for working circulation
Reset the boiler
Persistent overheating may require a system flush or replacement of the faulty component.
F5 – Low Water Pressure
Cause: The pressure in your central heating system is too low.
Fix:
Check the pressure gauge — ideal range is 1.0 to 1.5 bar
Use the external filling loop to repressurise
Reset the boiler
If this keeps happening, you might have a leak or need a pressure sensor replacement. We can help with both.
How to Reset Your Viessmann Boiler
Resetting your Viessmann boiler is usually straightforward:
Locate the reset button on the front panel
Press and hold it for 3–5 seconds
Wait for the system to restart
Only reset once. If the fault comes back, it’s time to get an expert involved.
Common Viessmann Boiler Repairs in Wokingham
At Thermo-Tec Plumbing and Heating, these are the most frequent Viessmann boiler issues we fix in Wokingham, Earley, Shinfield, and nearby:
Frozen condensate pipes during cold spells
Faulty ignition or flame detection
Pressure loss due to minor system leaks
Scale or sludge buildup in heat exchangers
PCB and sensor faults in older Viessmann models
When to Call us your Local Gas Safe Engineer in Wokingham
If you're seeing recurring fault codes, unusual noises, smells, or a total system shutdown, it's time to call a qualified heating engineer.
At Thermo-Tec Plumbing & Heating, we’re Gas Safe registered and experienced with Ideal fault codes. We cover Wokingham, Lower Earley, Woosehill, and surrounding villages.
Need a Viessmann Boiler Repair in Wokingham?
If your Viessmann boiler is showing a fault code or refusing to fire up, Thermo-Tec Plumbing and Heating is here to help.
📞 Call us today on 07850 116944 for expert Viessmann boiler repairs in Wokingham, Earley, Woodley, Winnersh, and surrounding areas.
FAQs – Viessmann Boiler Faults
Q: What does the F5 error mean on my Viessmann boiler?
A: F5 typically indicates low water pressure. You can usually fix this by topping up the system via the filling loop. If the pressure keeps dropping, it’s best to have your system checked for leaks.
Q: Can I fix the F2 flame failure code myself?
A: You can try resetting the boiler after checking the gas supply and ensuring the condensate pipe isn’t frozen. If the code returns, it’s time to call a Gas Safe engineer — it could be a faulty ignition or sensor issue.
Q: Is my Viessmann boiler too old to repair?
A: Many Viessmann models are very durable and can be repaired. However, if your boiler is 15 years or older, it may be more cost-effective to replace it with a newer, more efficient model.