Worcester Bosch C6 Fault

Worcester Bosch C6 Fault

The Worcester Bosch C6 fault code typically indicates an issue related to the fan speed being out of the expected range, either too fast or too slow, during the boiler’s operation. This fault is crucial because the fan plays a vital role in ensuring safe combustion by expelling harmful gases outside and drawing in fresh air for the combustion process. Here’s a closer look at the implications of the C6 fault code and how it can be addressed:

Causes of the C6 Fault Code

  1. Fan Operation Issues: The fan might not be operating within the required speed parameters due to wear and tear, mechanical faults, or blockages affecting its performance.
  2. Electrical Faults: Problems with the electrical connections or components related to the fan, such as the PCB (Printed Circuit Board) which controls the fan speed, can also trigger this fault code.
  3. Airflow Restrictions: Any restriction in the airflow, either due to blockages in the flue system or in the air intake, can impact the fan’s ability to operate correctly, leading to the C6 fault.

Troubleshooting and Resolving the C6 Fault Code

  1. Reset the Boiler: As a first step, try resetting the boiler to see if the fault clears. Sometimes, the issue might be temporary and can be resolved with a simple reset.
  2. Inspect the Fan: Check for any visible signs of damage or blockage that could be affecting the fan’s operation. This inspection should be carried out by a professional, as it involves dealing with critical components of the boiler.
  3. Check Electrical Connections: Ensure that all electrical connections to the fan and PCB are secure and not damaged. Loose or damaged wires can affect the fan’s speed control.
  4. Examine the Flue and Air Intakes: Look for any blockages or restrictions in the flue or air intake paths that could be impeding airflow. Clearing these paths can sometimes resolve the C6 fault.
  5. Professional Assessment: Given the complexity of diagnosing and repairing faults related to the fan and its control systems, it’s advisable to call a Gas Safe registered engineer. They have the expertise and equipment to safely diagnose the issue, whether it’s a fault with the fan itself, the PCB, or related components.
  6. Consider Component Replacement: Depending on the diagnosis, it might be necessary to replace the fan, the PCB, or other related components to resolve the C6 fault. Replacement parts should be of the correct specification and installed by a qualified professional to ensure safe and efficient boiler operation.


The Worcester Bosch C6 fault code signifies a problem with the fan speed, which is critical for the safe operation of the boiler. Addressing this fault requires a thorough inspection of the fan, electrical components, and airflow systems, typically carried out by a Gas Safe registered engineer. Regular maintenance can help prevent such issues by ensuring that all components are in good working order and that the system is clean and free from blockages.