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Vaillant Boiler Fault Codes
Browse the available Vaillant boiler fault codes in one place, then open the exact code page for the documented meaning, evidence limits and safe next steps.
Definitions can vary by model and region. Some codes remain unconfirmed; check the complete display, exact model and the page's sources before taking action.
Browse the parent brand page: Vaillant or compare across brands in the boiler codes across brands.
Fault codes
28
Code categories
9
Guides linked below
3
Code pages to start with
F22
Low water pressure. Applies only within the model and regional limits on the code page.
F28
No flame established during ignition. Applies only within the model and regional limits on the code page.
F29
Flame lost during operation and re-ignition unsuccessful. Applies only within the model and regional limits on the code page.
F25
Flue-gas temperature too high. Applies only within the model and regional limits on the code page.
F24
Boiler temperature rising too quickly. Applies only within the model and regional limits on the code page.
F32
Fan fault. Applies only within the model and regional limits on the code page.
Browse code categories
sensor codes
10 pages in this category. Open F00 as one example and check its model limits.
ignition codes
4 pages in this category. Open F27 as one example and check its model limits.
PCB and control codes
4 pages in this category. Open F61 as one example and check its model limits.
circulation codes
3 pages in this category. Open F23 as one example and check its model limits.
fan and flue codes
2 pages in this category. Open F25 as one example and check its model limits.
overheat codes
2 pages in this category. Open F20 as one example and check its model limits.
Code categories in this library
Counts refer to published code pages, not how often an appliance develops a fault.
sensor (10)
ignition (4)
PCB and control (4)
circulation (3)
fan and flue (2)
overheat (2)
More code pages
F22 meaning and guidance
Low water pressure
F23 meaning and guidance
Excessive flow-to-return temperature difference
F24 meaning and guidance
Boiler temperature rising too quickly
F25 meaning and guidance
Flue-gas temperature too high
F27 meaning and guidance
Flame signal detected with the burner off
F28 meaning and guidance
No flame established during ignition
F29 meaning and guidance
Flame lost during operation and re-ignition unsuccessful
F32 meaning and guidance
Fan fault
F75 meaning and guidance
Insufficient pressure change when the pump starts
F00 meaning and guidance
Interrupted flow-temperature sensor circuit
F01 meaning and guidance
Interrupted return-temperature sensor circuit
F10 meaning and guidance
Short circuit at the flow-temperature sensor
All fault codes in this cluster
28 code pages currently available for this brand and appliance. A severity label does not establish whether an appliance is safe to use.
| Code | Meaning | Issue type | Severity |
|---|---|---|---|
| F00 | Interrupted flow-temperature sensor circuit | sensor | Not assessed |
| F01 | Interrupted return-temperature sensor circuit | sensor | Not assessed |
| F10 | Short circuit at the flow-temperature sensor | sensor | Not assessed |
| F11 | Short circuit at the return-temperature sensor | sensor | Not assessed |
| F12 | Domestic-hot-water connection sensor short circuit | sensor | Not assessed |
| F13 | Short circuit at the cylinder-temperature sensor | sensor | Not assessed |
| F15 | Short circuit in the external flue-gas sensor circuit | sensor | Not assessed |
| F16 | Short circuit in the internal flue-gas sensor circuit | sensor | Not assessed |
| F20 | Thermal safety cut-out activated | overheat | Not assessed |
| F22 | Low water pressure | pressure level | Not assessed |
| F23 | Excessive flow-to-return temperature difference | circulation | Not assessed |
| F24 | Boiler temperature rising too quickly | circulation | Not assessed |
| F25 | Flue-gas temperature too high | fan flue | Not assessed |
| F27 | Flame signal detected with the burner off | ignition | Not assessed |
| F28 | No flame established during ignition | ignition | Not assessed |
| F29 | Flame lost during operation and re-ignition unsuccessful | flame loss | Not assessed |
| F32 | Fan fault | fan flue | Not assessed |
| F54 | Gas supply fault associated with F28 or F29 | ignition | Not assessed |
| F61 | Gas-valve control or electrical connection fault for F.061 | pcb control | Not assessed |
| F62 | Flame signal extinguishes too slowly after shutdown | ignition | Not assessed |
| F64 | Sensor conversion fault for F.064 | pcb control | Not assessed |
| F65 | Electronics temperature limit exceeded | pcb control | Not assessed |
| F67 | Flame-monitor fault | pcb control | Not assessed |
| F72 | Invalid flow-to-return sensor temperature difference | sensor | Not assessed |
| F75 | Insufficient pressure change when the pump starts | circulation | Not assessed |
| F76 | Primary heat-exchanger overheat protection activated for F.076 | overheat | Not assessed |
| F77 | Condensate-pump or external flue-flap interlock | condensate | Not assessed |
| F83 | Insufficient temperature rise detected after burner start | sensor | Not assessed |
Useful guides
Boiler Fault Codes: When to Stop and Call a Professional
First separate an emergency from a routine fault. A code needs the exact model and full display; it cannot by itself establish a safe reset or identify a part to replace.
When to Call an Appliance Engineer
Use the exact manual for permitted owner checks. Recurring faults, unsafe symptoms and work inside the appliance need appropriate professional help; emergencies need immediate action.
Why Your Boiler Keeps Losing Pressure
Use the pressure target and filling instructions for your exact boiler and installation. Repeated pressure loss needs investigation; a low reading alone does not identify a failed component.