What does the Viessmann Vitodens 100-W F33 fault code mean?
The F33 fault code on the Viessmann Vitodens 100-W indicates a problem with the pressure switch, which is responsible for monitoring the pressure within the boiler system. This fault can prevent the boiler from operating correctly, leading to heating and hot water issues.
Common Causes
- Blocked Pressure Switch Tubing: Debris or blockages in the tubing connected to the pressure switch can prevent it from functioning properly.
- Faulty Pressure Switch: The pressure switch itself may be defective or worn out, requiring replacement to restore normal operation.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer to diagnose and repair the issue, as working with gas appliances can be dangerous and requires professional expertise.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for addressing the F33 fault code, including parts and labour, is approximately £150 to £250. This includes the cost of a new pressure switch and the service charge for a qualified engineer.