What does the Viessmann Vitodens 050-W E335 fault code mean?
The E335 fault code indicates a problem with the system pressure relief valve, which may be stuck open or malfunctioning, leading to improper pressure regulation within the heating system. This can result in water leakage or pressure loss, affecting the boiler’s performance.
Common Causes
- Faulty Pressure Relief Valve: The valve may be damaged or worn out, causing it to fail in maintaining the correct pressure.
- System Overpressure: Excessive pressure in the system can lead to the valve opening unnecessarily, indicating a potential issue with the expansion vessel or other components.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer for this issue, as working on gas appliances can be dangerous. Attempting to fix the pressure relief valve without proper training may lead to further complications.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for replacing a faulty pressure relief valve on a Viessmann Vitodens 050-W is approximately £150 to £250. This includes the cost of the part and labour, as it requires a qualified engineer to ensure safe and proper installation.