Alpha E83/E84/E85 Faults

Alpha E83/E84/E85 Faults

The Alpha boiler error codes E83, E84, and E85 are associated with faults in the Printed Circuit Board (PCB), which is the central control unit of the boiler. These codes indicate various issues with the PCB that can affect the overall functionality and efficiency of the boiler. The PCB is crucial for managing and coordinating the operation of different components within the boiler, so faults in this area require prompt attention.

Causes of Alpha E83, E84, and E85 Error Codes

  1. E83: This code often points to a general communication problem within the boiler’s electronic components, possibly between the PCB and other parts of the boiler.
  2. E84: Indicates a failure in the connection to an external probe, such as an outdoor temperature sensor, which can lead to inefficient boiler operation due to inaccurate temperature readings.
  3. E85: This code typically signifies a more specific issue with the PCB, such as a failure in its internal circuitry or programming errors that affect its ability to control the boiler effectively.

Troubleshooting and Resolving Alpha E83, E84, and E85 Error Codes

  1. Reset the Boiler: Sometimes, a simple reset can clear temporary communication glitches or minor PCB errors. Refer to your boiler’s manual for the correct reset procedure.
  2. Check Electrical Connections: Ensure all electrical connections, especially those related to the PCB and external probes, are secure and in good condition. Loose or damaged connections can cause these error codes.
  3. Inspect External Probes (E84): For E84 errors, check any connected external probes for damage or disconnection. Ensure they are properly installed and functioning.
  4. Professional Assessment: Given the complexity of PCB-related issues and the risk of causing further damage, it’s advisable to contact a Gas Safe registered engineer for a thorough diagnosis. A professional can assess whether the PCB needs reprogramming, repairing, or replacing.
  5. Consider PCB Replacement: In some cases, especially for E85 errors, the PCB may need to be replaced. This is a significant repair that should only be conducted by a qualified technician to ensure correct installation and programming.
  6. Regular Maintenance: Prevent future PCB-related issues by ensuring your boiler undergoes regular professional maintenance. This can help identify potential problems early and maintain optimal boiler performance.


Error codes E83, E84, and E85 on an Alpha boiler indicate significant issues with the PCB that can impact the boiler’s operation. Due to the technical nature of these faults, professional diagnosis and repair are essential. Regular maintenance can help detect early signs of PCB problems, contributing to the longevity and efficiency of your boiler system.