F.63 Flue gas temperature limiter tripped

What the control is telling you

Burner in a fault state after the flue gas temperature limiter responded.

Applies to: Vitodens 200-W B2HE 85, 120, 150, 199

Likely causes

• Low water level
• Wrong expansion tank pre-charge
• Insufficient flow
• 3-way valve fault

Test and repair steps

1. Check the system fill level.
2. Check expansion tank pre-charge and adjust to system pressure.
3. Verify flow is sufficient (flow sensor and circulation pump).
4. Test the 3-way diverter valve in the actuator test.
5. Vent the system.
6. Reset only after the flue system has cooled down.

Models that show this code

4 models in Vitodens 200-W B2HE

Other codes on the same units

• F.574 HC1 room sensor not available
• F.58 Room temperature sensor short circuit
• F.59 Supply voltage too low, burner locked out
• F.62 High limit safety cut-out tripped
• F.666 DHW preheating sensor TS3 open circuit
• F.667 DHW preheating sensor TS3 short circuit
• F.668 DHW reheating sensor TS4 open circuit
• F.669 DHW reheating sensor TS4 short circuit