Viessmann Error Code F.63: Flue gas temperature limiter tripped (Boiler)
Viessmann error code F.63 on a boiler means: Flue gas temperature limiter tripped. It is also called Viessmann diagnostic code F.63.
Homeowner? What Viessmann code F.63 means for you
Stop and call Your boiler is reporting: Flue gas temperature limiter tripped. This code is a safety shutdown. Turn the boiler off and call a licensed technician. Do not keep resetting it. If you smell gas, leave the house and call your gas utility or 911 from outside.
Safe things you can check yourself
- Check the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
- Make sure the unit has power: its on/off switch (often looks like a light switch near the unit) is ON and the breaker in the electrical panel is not tripped.
Call (647) 657-2977Book a service call
Licensed technicians serving Vaughan, Toronto and the GTA.
What does Viessmann error code F.63 mean?
Burner in a fault state after the flue gas temperature limiter responded.
Applies to: Vitodens 200-W B2HE 85, 120, 150, 199
Common causes of Viessmann code F.63
- Low water level
- Wrong expansion tank pre-charge
- Insufficient flow
A technician checks these and 1 other possible causes on site before replacing any part.
Viessmann models that use code F.63
B2HE-85B2HE-120B2HE-150B2HE-199
Other Viessmann Boiler codes
All Viessmann Boiler error codes →
Viessmann code F.63: homeowner questions
What does Viessmann code F.63 mean?
Flue gas temperature limiter tripped. Burner in a fault state after the flue gas temperature limiter responded.
Is it safe to keep using my boiler with code F.63?
No. Code F.63 is a safety shutdown, so keep the boiler off until a licensed technician has checked it.
Can I reset Viessmann code F.63 myself?
Do not keep resetting it. Repeated resets can hide a safety problem; a licensed technician needs to find the cause.
Who can fix Viessmann code F.63 near me?
Aurora Star Tech Inc. repairs Viessmann boilers in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.
Homeowner help: Boiler Not Heating: What to Check
Troubleshooting guides
- Condensing/corrosion of conventional boiler All brands · Boiler
- No heat or some zones cold All brands · Boiler
- Noise All brands · Boiler
- Poor heat / circulation All brands · Boiler
- Relief valve weeps every cycle / pressure climbs All brands · Boiler
- Short cycling / wasted fuel All brands · Boiler
- Symptoms of air in system All brands · Boiler
- Uneven heating All brands · Boiler
- Won't fire All brands · Boiler
- Acknowledged fault comes back Viessmann · Boiler
- Actuator test: drive fan, burner, pump and 3-way valve by hand Viessmann · Boiler
- Clear the service message (P.1 / P.8) Viessmann · Boiler
- Condensate not draining, burner shuts down Viessmann · Boiler
- Filling and purging programs (20 min auto-stop) Viessmann · Boiler
- Lag boilers lose contact with lead boiler (cascade) Viessmann · Boiler
- Open the Service menu (password viservice) Viessmann · Boiler
- Where the fault history lives Viessmann · Boiler
Source: Viessmann Vitodens 200-W B2HE 85/120/150/199 Service Instructions 6167 813-24 (09/2026), Fault messages, p.62-73. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.