How to Fix Vaillant F75 Fault Code (UK)
Vaillant showing F75 — Pump/pressure sensor. UK diagnosis, likely spare (pressure sensor 0020059717) and step-by-step reset.
What the code means
F75 on a Vaillant indicates pump/pressure sensor. The boiler locks out to protect the heat exchanger and, on gas faults, to comply with the Gas Safety (Installation and Use) Regulations. Always reset to confirm the code is live, not historical.
Likely spare
The most common fix is the pressure sensor 0020059717. Check the exploded diagram against the GC number on the data plate before ordering — Vaillant revised parts on Vaillant units mid-production.
Fix procedure
Bleed pump, replace sensor if reads 0.0 with system at 1.5 bar.
Log the fault and reset. If the code returns within 24 hours, escalate to full electrical diagnosis with a manometer and multimeter.
Frequently asked questions
- Can I reset F75 myself?
- You can press the reset button up to 3 times. If F75 returns, the boiler needs a Gas Safe engineer — it is illegal to repair gas components without registration.
- Is the part covered under warranty?
- Vaillant standard warranty is 2–10 years depending on model. Registered installations get the full term. Check the sticker inside the case.
Browse boiler spares — 14,820 live parts.
View Boiler Spares