BoilerFaultCodesVaillant F.22 Fault Code
Also written as F22 — same fault.
The Vaillant F.22 fault code means: your boiler has detected that there is not enough water pressure in the system to operate safely, causing it to shut down to prevent overheating.. It appears on 57 Vaillant models in our database.
Technical description: Dry fire protection | No water in appliance, pump cable defective, pump blocked or defective, pump output too low
What causes the Vaillant F.22 fault?
This fault occurs when the boiler's internal sensor detects that the system pressure has dropped too low for the unit to heat water safely. The most common reason is a slow leak somewhere in your radiator network or a faulty expansion vessel that can no longer regulate pressure correctly. Without enough water to circulate, the boiler shuts down to prevent the heat exchanger from overheating or sustaining permanent damage.
This fault is more common in autumn and winter when the heating is first turned on, as the increased pressure of hot water can expose small leaks or reveal that the system lost pressure while sitting idle during the summer.
DIY fix possible
Locate the silver braided filling loop hoses underneath or near the boiler.Open the two small valves on the filling loop to allow water into the system.Watch the pressure gauge on the front of the boiler until it reaches between 1.0 and 1.5 bar, then close both valves tightly.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Vaillant models that show the F.22 fault code
Click a model for the full fault code list and model-specific repair notes.
- aquaPLUS Repair: £100-£350
- Atmomax Repair: £80-180
- Combi Compact 242EB Repair: £0-120
- Combi Compact 282EB Repair: £0-160
- ecoFIT pure Repair: £80-150
- ecoFIT Pure 412 Repair: £0-120
- ecoFIT Pure 418 Repair: £80-150
- ecoFIT Pure 425 Repair: £80-150
- ecoFIT Pure 435 Repair: £80-150
- ecoFIT Pure 825 Repair: £80-150
- ecoFIT Pure 830 Repair: £60-120
- ecoFIT Pure 835 Repair: £80-150
- ecoMAX Repair: £0-180
- ecoMAX 613 Repair: £0-280
- ecoMAX 618 Repair: £0-280
- ecoMAX 622 Repair: £0-280
- ecoMAX 635 Repair: £0-280
- ecoMAX 824E Repair: £0-280
- ecoMAX 828E Repair: £0-280
- Ecomax Condensing 600/800 series Repair: £80-120
- ecoMAX Pro 28E Repair: £0-120
- ecoMAX System 612 Repair: £0-280
- ecoTEC Repair: £0-120
- ecoTEC exclusive Repair: £0-120
- ecoTEC plus Repair: £0-120
- ecoTEC Plus 615 Repair: £0-120
- ecoTEC Plus 620 Repair: £0-120
- ecoTEC Plus 625 Repair: £0-120
- ecoTEC Plus 630 Repair: £0-120
- ecoTEC Plus 635 Repair: £0-120
- ecoTEC Plus 65 Repair: £0-120
- ecoTEC Plus 826 Repair: £80-150
- ecoTEC Plus 832 Repair: £0-120
- ecoTEC Plus 836 Repair: £0-120
- ecoTEC Plus 840 Repair: £0-120
- ecoTEC Plus 938 Repair: £0-120
- ecoTEC plus Aquaplus Repair: £120-250
- ecoTEC plus Regular Repair: £80-150
- ecoTEC plus System Repair: £80-150
- ecoTEC Pro Repair: £0-160
- ecoTEC Pro / ecoTEC Plus Repair: £0-160
- ecoTEC Pro 24 Repair: £0-160
- ecoTEC Pro 28 Repair: £0-160
- ecoTEC Pro 30 Repair: £80-150
- ecoTEC sustain Repair: £0-120
- Home System Repair: £0-160
- Thermocompact Repair: £100-£350
- Turbomax Plus 824/828E Repair: £0-180
- Turbomax Plus 824/828E Repair: £80-120
- Turbomax Plus 828 Repair: £120-350
- Turbomax Plus 828 Repair: £0-120
- Turbomax Plus 828 E Repair: £0-180
- Turbomax Plus 828 E Repair: £80-120
- Turbomax Plus VUW 242E Repair: £0-180
- Turbomax Plus VUW 242E Repair: £80-120
- Turbomax Plus VUW 242EH Repair: £0-180
- Turbomax Plus VUW 242EH Repair: £80-120
Source
Vaillant F.22 fault code information on this page is sourced and cross-checked against the official Vaillant service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026