F.75Vaillant
Vaillant F.75: no pressure rise detected when the pump started
Checked against Vaillant's own documentation: Vaillant: boiler fault codes list and 3 more sources. Last reviewed October 2026. How we check
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
- 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.