Baxi Common Faults and Error Codes

Baxi Common Faults and Error Codes

Baxi boilers, like other brands, use a system of fault and error codes to indicate specific issues within the boiler’s operation. Understanding these codes can help in diagnosing problems and determining whether professional help is needed for repairs. Here are some common Baxi boiler fault and error codes and their meanings:

  1. E133: Gas Supply Fault – Indicates a problem with the gas supply, such as it being turned off, low gas pressure, or a fault with the gas valve.
  2. E119: Low Water Pressure – Signals that the water pressure in the system has fallen below the minimum required level, often due to leaks or natural pressure loss.
  3. E168: Electrical Fault – Suggests an issue with the boiler’s electrical supply, possibly due to an electrical surge, faulty connections, or a problem with the boiler’s internal electrical components.
  4. E125: Circulation Fault (Primary) – Indicates a problem with the circulation of water within the boiler, which could be due to a faulty pump or blockages in the system.
  5. E128: Flame Failure – Occurs when the boiler fails to detect a flame after ignition attempts, which can be due to issues with the ignition system, gas supply, or flue.
  6. E160: Fan Fault – Indicates a problem with the boiler’s fan, which is essential for removing harmful gases and ensuring fresh air for combustion.
  7. E1: NTC Thermistor Faults – These errors (such as E1 followed by another number like 30 or 31) relate to faults with the thermistors (temperature sensors), indicating issues with temperature readings within the boiler.
  8. E78: Water Pressure Sensor Fault – Indicates a fault with the sensor that measures water pressure, possibly due to damage or incorrect readings.

Troubleshooting and Resolution

  • E133 (Gas Supply Fault): Check that the gas supply to the house is on and that other gas appliances are working. If the supply is fine, the issue may lie with the boiler’s gas valve or ignition system.
  • E119 (Low Water Pressure): Check the boiler’s pressure gauge and repressurize the system if necessary. Look for visible leaks in the system that may need to be repaired.
  • E168 (Electrical Fault): Ensure the boiler’s electrical connections are secure and that there hasn’t been a recent power surge. If the problem persists, consult a professional as the boiler’s PCB may need inspection.
  • E125 (Circulation Fault): Check for any obvious blockages and ensure the pump is functioning. This may require professional assistance to resolve.
  • E128 (Flame Failure): Inspect the flue for blockages and ensure there are no issues with the gas supply. A Gas Safe registered engineer should address persistent flame failures.
  • E160 (Fan Fault): The fan will likely need to be inspected and possibly replaced by a professional.
  • E1 NTC Thermistor Faults: These sensors may need cleaning or replacing. Due to the need for accurate diagnostics, professional help is recommended.
  • E78 (Water Pressure Sensor Fault): The sensor may need cleaning or replacing. This should be done by a professional.


While some Baxi boiler errors can be resolved with simple checks and resets, many will require professional diagnosis and repair, especially when dealing with gas supply issues, electrical faults, or component failures. Regular maintenance by a qualified engineer can help prevent many common issues and ensure your boiler operates safely and efficiently.