What does the Baxi Megaflo E840 fault code mean?
The E840 fault code on a Baxi Megaflo indicates a safety fault within the central heating (CH) system. This typically suggests that there is an issue that could compromise the safe operation of the boiler.
Common Causes
- Low Water Pressure: Insufficient water pressure in the system can trigger safety mechanisms to prevent overheating or damage.
- Faulty Safety Valve: A malfunctioning safety valve may not operate correctly, leading to safety fault codes being displayed.
Can I fix it myself? (DIY)
While you can check the water pressure and attempt to reset the boiler, it is strongly advised to call a Gas Safe Engineer for any gas or electrical issues to ensure safety and compliance with regulations.
Estimated Repair Cost (2026 UK Prices)
Repair costs for the E840 fault can range from £150 to £300, depending on whether the issue is low water pressure or a faulty safety valve that needs replacement.