Potterton Common Fault and Error codes

Potterton Common Fault and Error codes

Potterton boilers, like those of other manufacturers, use a system of fault and error codes to help diagnose issues within the boiler. These codes provide a quick way for homeowners and engineers to identify specific problems, facilitating faster troubleshooting and repairs. Here’s a rundown of some common Potterton boiler fault and error codes and their general meanings:

  1. E110: Overheat – This error occurs when the boiler’s water temperature exceeds the maximum safe limit. It could be due to a problem with the thermostat, pump, or restricted water flow causing overheating.
  2. E119: Low Water Pressure – Indicates that the water pressure in the system has dropped below the minimum required level, often due to leaks or natural pressure loss.
  3. E125: Circulation Fault – Suggests a problem with water circulation in the system, potentially caused by a faulty pump or blockages that restrict water flow.
  4. E133: Ignition Failure – This code appears when the boiler fails to ignite, which could be due to issues with the gas supply, ignition electrodes, or a blocked flue.
  5. E160: Fan Fault – Points to a problem with the boiler’s fan, which is crucial for venting exhaust gases and drawing in air for combustion.
  6. E20: Central Heating Thermistor Sensor Fault – Indicates a problem with the sensor that measures the temperature of water in the central heating system.
  7. E28: Flue Thermistor Fault – This error code signifies an issue with the flue thermistor, which measures the temperature of gases in the flue.
  8. E40: Central Heating (CH) Return Thermistor Fault – Indicates a fault with the thermistor that measures the temperature of water returning to the boiler from the central heating system.
  9. E78: Water Pressure Sensor Fault – Points to a problem with the sensor that monitors the system’s water pressure.
  10. E83, E84, E85: PCB Fault – These codes are related to issues with the Printed Circuit Board (PCB), the control center for the boiler’s operations.

Troubleshooting and Resolution

  • E110 (Overheat) and E125 (Circulation Fault): Check for blockages, ensure the pump is operational, and verify that the thermostat is functioning correctly.
  • E119 (Low Water Pressure): Re-pressurize the system if necessary and check for leaks.
  • E133 (Ignition Failure): Ensure there’s a gas supply to the boiler, check the condition of the ignition electrodes, and make sure the flue is clear.
  • E160 (Fan Fault): Verify the fan’s operation and check for any obstructions or electrical issues affecting its performance.
  • E20, E28, E40 (Thermistor Faults): Inspect the relevant thermistors for damage or faulty connections and replace if necessary.
  • E78 (Water Pressure Sensor Fault): Check the water pressure sensor for damage or incorrect readings and consider replacement if faulty.
  • E83, E84, E85 (PCB Fault): Given the complexity of PCB issues, professional diagnosis and repair are typically required.


Potterton boiler fault and error codes are essential tools for identifying issues within the heating system. While some problems can be addressed with basic troubleshooting, others necessitate professional intervention due to their complexity or the need for specialized knowledge and equipment. Regular maintenance by a qualified engineer can help prevent many common faults and ensure the boiler operates efficiently and safely.