Vaillant Boiler Error Codes: Full UK Guide (2025)
A complete, UK-focused breakdown of Vaillant boiler fault codes — including F.22, F.75, F.28, F.29, F.27, and ignition issues across ecoTEC, TurboMax and older models.
Vaillant Boiler Error Codes: Full UK Guide (2025)
Vaillant is one of the most common boilers in the UK — especially the ecoTEC Plus, ecoTEC Pro, TurboMax, Home, and Pure ranges found across London, Birmingham, Manchester, Leeds, Glasgow, Bristol and Liverpool.
This guide clearly explains what the major Vaillant fault codes mean, how to fix them, and typical UK repair costs for 2025.
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Most Common Vaillant Error Codes in 2025
F.22 – Low Water Pressure
The #1 Vaillant fault in the UK.
Causes:
- Pressure below 1 bar
- Leak in the system
- Radiators need bleeding
Fix:
- Repressurise system
- Bleed radiators
- Check for visible leaks
Typical UK Cost: £0–£150
F.28 – Ignition Failure
Common during cold weather.
Causes:
- Frozen condensate pipe
- Faulty flame sensor
- Gas supply issue
Cost: £120–£300
F.75 – Pump or Pressure Sensor Fault
Very common on ecoTEC models.
Meaning: Pump not detecting pressure rise.
Fix:
- Replace pump
- Clean or replace pressure sensor
- Remove sludge
Cost: £160–£350
F.29 – Flame Loss While Running
Causes:
- Low gas pressure
- Blocked flue
- Faulty ignition lead
Cost: £120–£260
Additional Vaillant Fault Codes
F.27 – Flame Detection Error
Often triggered by moisture inside the burner.
Cost: £120–£240
F.61 / F.62 – Gas Valve Error
Gas valve not responding or stuck.
Cost: £220–£420
F.83 / F.84 – Flow/Return Temperature Fault
Fix: Replace flow or return sensor.
Cost: £80–£160
F.64 – PCB or Sensor Communication Fault
Requires diagnosis.
Cost: £250–£480
Frozen Condensate Pipe Issues (Common in UK Winter)
Many ignition faults (F.28, F.29) appear when outdoor condensate pipes freeze.
Fix:
- Pour warm water over pipe
- Reset boiler
- Fit pipe insulation
Cost: £0–£80
Vaillant Boiler Repair Costs (UK 2025)
| Fault | Typical UK Cost |
|---|---|
| Low pressure (F.22) | £0–£150 |
| Ignition failure (F.28) | £120–£300 |
| Pump failure (F.75) | £160–£350 |
| Gas valve (F.61/F.62) | £220–£420 |
| PCB communication (F.64) | £250–£480 |
| Sensor replacement | £80–£160 |
| Annual boiler service | £70–£90 |
Should You Repair or Replace a Vaillant Boiler?
You may want to consider replacement if:
- Boiler is 12+ years old
- Multiple F.28/F.29 occurrences
- F.75 pump issues recur
- Repair cost > £500
Protect yourself from future breakdowns:
Final Advice
Vaillant boilers are reliable, but common UK faults include F.22, F.28, F.29, and F.75, especially in cold months.
For fewer breakdowns:
- Keep system pressure stable
- Insulate outdoor pipes
- Book annual servicing
Explore protection options: