What does the Baxi 600 Series E390 fault code mean?
The E390 fault code on the Baxi 600 Series indicates that there is low water pressure in the domestic hot water (DHW) system. This can lead to insufficient hot water supply and may require immediate attention to restore proper function.
Common Causes
- Low System Pressure: The pressure in the heating system may have dropped below the minimum required level, often due to leaks or bleeding radiators.
- Faulty Pressure Relief Valve: A malfunctioning pressure relief valve can cause water to escape, leading to low pressure in the system.
Can I fix it myself? (DIY)
You can attempt to fix low water pressure by checking the pressure gauge on the boiler and re-pressurising the system using the filling loop if necessary. However, if you suspect a leak or if the issue persists, it is essential to call a Gas Safe Engineer for further diagnosis and repair.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for addressing the E390 fault could range from £100 to £250, depending on whether it involves simply re-pressurising the system or replacing a faulty component like the pressure relief valve.