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BoilerCodes
F.75
Vaillant fault code

Vaillant F.75: no pressure rise detected when the pump started

Check these first, then call an engineer

When the boiler's pump starts, the water pressure should rise slightly. It didn't, so the boiler stopped. Vaillant lists a faulty pressure sensor or pump, air in the system, or too little water as causes.

Recommended pressure when cold for Vaillant boilers: 1.0 to 2.0 bar.

What you can safely do

  1. Read the pressure gauge with the system cold. If it is below 1.0 bar, top it up to between 1.0 and 2.0 bar as you would for F.22.

Call a Gas Safe engineer if

  • The pressure is already between 1.0 and 2.0 bar.
  • The code comes back after topping up.
Find a Gas Safe engineer near you Opens the official Gas Safe Register search.

Applies to: ecoTEC plus. Codes can differ between models, so check your manual.

What F.75 means on each Vaillant model

From Vaillant's own fault tables. Your model name is usually on the front of the boiler or in the user manual.

ModelMeaningCauses listed for engineers
ecoTEC plusNo pressure change detected when starting the pumpWater pressure sensor and/or pump defective, air in the heating installation, insufficient water in the boiler

Common questions about Vaillant F.75

Can I fix F.75 myself?

Only the pressure check. If the pressure is fine and F.75 stays, the pump or pressure sensor needs a Gas Safe registered engineer.

Is F.75 the same as F.22?

No. F.22 means the pressure is too low. F.75 means the boiler didn't see the pressure rise it expects when the pump starts, which usually points to the pump or sensor.

Nearby Vaillant codes

F.22F.28F.29F.83F.23F.72F.20F.25

See all 36 Vaillant codes

Sources