Baxi E125 Fault

Baxi E125 Fault

The Baxi E125 error code indicates a primary circulation fault within the boiler system. This issue arises when there’s a problem with the flow of water through the boiler’s primary heat exchanger, often due to poor circulation. The fault can stem from several causes, affecting the boiler’s ability to heat water efficiently and could lead to overheating if not addressed promptly.

Causes of the E125 Error Code

  1. Blocked Heat Exchanger: Over time, the heat exchanger can accumulate sludge, debris, or scale, leading to blockages that impede water flow.
  2. Faulty Pump: The pump circulates water through the boiler and heating system. If it’s failing or set to an incorrect speed, circulation can be affected.
  3. Airlocks in the System: Air trapped within the heating system can prevent water from circulating properly, leading to areas of poor flow.
  4. Closed or Partially Closed Valves: Valves within the heating system that are not fully open can restrict water flow.
  5. System Pressure Issues: Both excessively high and low system pressure can impact water circulation.

Troubleshooting and Resolving the E125 Error Code

  1. Check System Pressure: Ensure the boiler’s pressure gauge is within the recommended range (usually between 1 and 1.5 bar). Adjust the pressure if necessary by repressurizing the system.
  2. Bleed Radiators: Release any trapped air from the radiators and heating system to eliminate potential airlocks.
  3. Inspect and Adjust Valves: Verify that all valves in the heating system are fully open to allow proper water flow.
  4. Examine the Pump: Listen for any unusual noises from the pump that might indicate it’s failing or check if it’s warm to the touch, suggesting it’s working. Adjustments or replacements should be carried out by a professional.
  5. Flush the System: If a blocked heat exchanger is suspected, a system flush may be required to remove sludge, debris, or scale. This is a task for a Gas Safe registered engineer.
  6. Reset the Boiler: After addressing potential issues, reset the boiler to clear the error code and attempt normal operation.
  7. Seek Professional Assistance: Due to the complexity of diagnosing and fixing circulation faults, consulting a Gas Safe registered engineer is advisable. They can provide a comprehensive assessment and undertake necessary repairs or adjustments.


The Baxi E125 error code is a significant indication of a circulation fault within the boiler system, necessitating prompt attention to ensure efficient and safe boiler operation. While homeowners can perform basic checks and adjustments, resolving circulation issues often requires professional intervention. Regular maintenance and servicing by a qualified technician can help prevent such problems, ensuring your heating system remains reliable and efficient.