Appliance hub
Vaillant Boiler Fault Codes
Browse the available Vaillant boiler fault codes in one place, then open the exact code page for the likely meaning, safe first steps, and when to stop troubleshooting.
Browse the parent brand page: Vaillant or compare across brands in the global boiler fault-code hub.
Fault codes
28
Issue categories
6
Related guides
3
Most common faults to check first
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.
Common problems in this cluster
sensor problems
Start with F64, then compare 10 related code pages in this cluster.
overheat problems
Start with F25, then compare 3 related code pages in this cluster.
gas valve problems
Start with F54, then compare 2 related code pages in this cluster.
circulation problems
Start with F24, then compare 1 related code pages in this cluster.
flame-loss problems
Start with F27, then compare 1 related code pages in this cluster.
low-pressure problems
Start with F22, then compare 1 related code pages in this cluster.
Common fault categories
sensor (11)
overheat (4)
gas valve (3)
circulation (2)
flame-loss (2)
low-pressure (2)
Most searched / most useful codes
F32 meaning and fix
Fan, flue, or air pressure sensing problem
F24 meaning and fix
Water circulation or pump performance issue
F25 meaning and fix
Overheat protection fault
F27 meaning and fix
Flame detection has been lost during operation
F28 meaning and fix
The boiler failed during ignition
F29 meaning and fix
The boiler lost flame while running
F75 meaning and fix
Water circulation or pump performance issue
F22 meaning and fix
The heating system pressure is too low
F23 meaning and fix
System water pressure is too low
F20 meaning and fix
the boiler has reached an overheat or high-temperature safety limit.
F64 meaning and fix
the boiler has detected an internal sensor, electronics, or control-reading fault.
F54 meaning and fix
Gas supply control or gas valve issue
All fault codes in this cluster
28 code pages currently available for this brand and appliance cluster.
| Code | Meaning | Issue type | Severity |
|---|---|---|---|
| F00 | Flow temperature sensor circuit is interrupted | sensor | medium |
| F01 | Return temperature sensor circuit is interrupted | sensor | medium |
| F10 | Flow temperature sensor has short-circuited | sensor | medium |
| F11 | Return temperature sensor has short-circuited | sensor | medium |
| F12 | Cylinder or storage sensor circuit is interrupted | sensor | medium |
| F13 | Cylinder or storage sensor has short-circuited | sensor | medium |
| F15 | External sensor signal is interrupted on selected systems | sensor | medium |
| F16 | External sensor signal has short-circuited on selected systems | sensor | medium |
| F20 | the boiler has reached an overheat or high-temperature safety limit. | overheat | high |
| F22 | The heating system pressure is too low | low pressure | medium |
| F23 | System water pressure is too low | low pressure | medium |
| F24 | Water circulation or pump performance issue | circulation | high |
| F25 | Overheat protection fault | overheat | high |
| F27 | Flame detection has been lost during operation | flame loss | high |
| F28 | The boiler failed during ignition | ignition | high |
| F29 | The boiler lost flame while running | flame loss | high |
| F32 | Fan, flue, or air pressure sensing problem | fan flue | high |
| F54 | Gas supply control or gas valve issue | gas valve | high |
| F61 | Gas supply control or gas valve issue | gas valve | high |
| F62 | Gas supply control or gas valve issue | gas valve | high |
| F64 | the boiler has detected an internal sensor, electronics, or control-reading fault. | sensor | high |
| F65 | The boiler has overheated or hit a high temperature limit | overheat | high |
| F67 | Control board or internal communication fault | pcb control | high |
| F72 | A boiler sensor is giving an invalid reading | sensor | medium |
| F75 | Water circulation or pump performance issue | circulation | high |
| F76 | The boiler has overheated or hit a high temperature limit | overheat | high |
| F77 | Condensate, drainage, or pump protection issue | condensate | medium |
| F83 | the boiler is not seeing the expected temperature change from its flow or return sensors. | sensor | medium |
Useful guides
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.