Brand hub
Vaillant Fault Codes
Check Vaillant boiler fault codes and understand which steps are safe for homeowners and which need an engineer. Use this hub to move into the right appliance section, then open the exact fault code page for quick meaning, safe first checks, and escalation advice.
Appliance hubs
1
Fault code pages
28
Guides linked in
3
Appliance types
Global appliance category hubs
Most searched fault codes
F22
Low system pressure lockout and pressure-loss checks.
F28
Ignition fault when boiler fails to light.
F29
Flame-loss fault after ignition attempt.
F25
Overheat protection lockout linked to circulation risk.
F24
Circulation/temperature rise fault during heating demand.
F32
Fan speed/fan control issue affecting safe operation.
Most common fault families
sensor (11)
overheat (4)
gas valve (3)
circulation (2)
flame-loss (2)
low-pressure (2)
Popular priority codes
F32 for Boiler
Fan, flue, or air pressure sensing problem
F24 for Boiler
Water circulation or pump performance issue
F25 for Boiler
Overheat protection fault
F27 for Boiler
Flame detection has been lost during operation
F28 for Boiler
The boiler failed during ignition
F29 for Boiler
The boiler lost flame while running
F75 for Boiler
Water circulation or pump performance issue
F22 for Boiler
The heating system pressure is too low
F23 for Boiler
System water pressure is too low
F20 for Boiler
the boiler has reached an overheat or high-temperature safety limit.
F64 for Boiler
the boiler has detected an internal sensor, electronics, or control-reading fault.
F54 for Boiler
Gas supply control or gas valve issue
Related guides
Practical background guides connected to this brand's fault-code pages.
Boiler Fault Codes: When to Stop and Call a Professional
Boiler issues need a more cautious approach than most white goods, especially where gas, combustion, or repeated lockouts are involved.
When to Call an Appliance Engineer
Guidance on recognising when simple checks have been exhausted and it is time to arrange a repair.
Why Your Boiler Keeps Losing Pressure
Learn the difference between a one-off pressure drop and repeated pressure loss, plus the safe top-up and recheck advice that stays within normal user controls.