Boiler shows E11, pressure gauge is high (often above 3 bar), discharge from pressure relief valve may be visible.
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Possible Causes
How to Fix / Troubleshooting
Safety: Hot water may discharge from the safety valve; keep clear of the discharge pipe. Allow system to cool before venting.
User checks:
- Ensure the filling loop valves are fully closed and the hose is disconnected if removable.
- Bleed one or two radiators to reduce pressure back to around 1.5 bar when cold.
- Reset the boiler once pressure is normal.
Engineer checks:
- Test the expansion vessel pre-charge; recharge to the value specified by EHC (commonly around 0.8–1.0 bar) or replace if the diaphragm has failed.
- Inspect the pressure relief valve for debris or damage; replace if it continues to drip after pressure is corrected.
- Check for blockages in the expansion pipework between boiler and vessel.
Do not leave the system running at high pressure; this can damage components and cause leaks.
Repair Difficulty
Required Part
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