What does the Baxi 600 Series E420 fault code mean?
The E420 fault code on the Baxi 600 Series indicates a blockage in the flue system that is preventing the proper venting of flue gases. This issue can lead to unsafe operating conditions and requires immediate attention to ensure safe boiler operation.
Common Causes
- Blocked Flue Pipe: Debris, bird nests, or snow can obstruct the flue pipe, preventing exhaust gases from escaping.
- Flue Terminal Issues: The flue terminal may be incorrectly installed or damaged, leading to inadequate ventilation and triggering the fault code.
Can I fix it myself? (DIY)
It is strongly advised to call a Gas Safe Engineer to address this issue, as working with gas appliances and flue systems can be dangerous. Attempting to fix it yourself may lead to safety hazards or further damage.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for resolving the E420 fault could range from £150 to £300, depending on the specific cause of the blockage and whether parts need replacing or just cleaning. This estimate includes the cost of a Gas Safe Engineer’s visit and any necessary repairs.