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Vaillant · Error F75

Vaillant F75 — what it means

Pressure sensor or pump fault — the boiler didn't see a pressure change when the pump started.

⚠ This is the likely cause from the code — a Gas Safe registered engineer confirms it on site. If you can smell gas, stop and ring 0800 111 999.

✅ Try these first — they're free

Often clears it without a callout:

  • Check the pressure gauge is between 1 and 1.5 bar; top up if low
  • Press reset once

🔧 If that doesn't fix it

The likely cause is one of these — the engineer confirms which:

  • Failed pressure sensor
  • Seized or failing pump
  • Air trapped in the system

Most likely part: Pressure sensor

⚠ Worth knowing

  • On Vaillant F75 the sensor and the pump often fail as a pair — it's worth pricing both so there isn't a second visit
Fixed repair price
£170
Part + labour, no surprise callout fee. You only pay if you go ahead.
Book a Gas Safe engineer
You pick from the 3 nearest vetted engineers. Your choice gets first refusal; if they don't take it within a few hours it moves to the next nearest automatically — and we keep you posted.

Other Vaillant fault codes

Vaillant F22Low water pressure / dry-fire protection — not enough water …Vaillant F28Ignition failure — the boiler couldn't establish a flame at …