E125 — Poor Primary Circulation

What does E125 mean?

This code indicates a problem with the boiler's internal water circulation. It can appear if the boiler temperature doesn't change enough after ignition or if it overheats rapidly despite modulating, suggesting poor flow. The display shows 'E1' alternating with '25'.

• Blockage in the primary heating circuit.
• Malfunctioning pump.
• Air trapped in the system.
• Three-way valve stuck or not operating correctly.

Click steps to track your progress.

1. 1

   Turn the selector switch to the 'Reset' position and hold for 5 seconds.

2. 2

   Ensure all radiator valves are open, especially on the primary heating circuit.

3. 3

   Vent radiators to release any trapped air in the system.

4. 4

   If the error persists, contact a qualified heating engineer to check the pump and circulation.