Biasi Advance Plus 35C ERP Fault codes & diagnostics

35 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.

Combi Natural Gas 2015-present
GC Number 47-583-37
Download the Biasi Advance Plus 35C ERP manualThe official installation and service manual (PDF), the document these fault codes were read from. PDF

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Severity at a glance

Each cell = one fault code. Hover to identify.
3 Emergency 24 High 5 Medium 3 Low
Fault codes

All 35 documented codes

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An 11

Your boiler is struggling to light its burner or cannot detect that a flame has been successfully lit, preventing it from heating your water.

High DIY-safe £90-280

What to check first

  1. Check if other gas appliances, like your hob, are working to ensure gas is reaching the property.
  2. Verify that your prepaid gas meter has credit if applicable.
  3. Press and hold the 'Reset' button for five seconds to see if the boiler restarts.

Parts commonly replaced

  • Ignition Electrode
  • Flame Sensing Probe
  • Gas Valve

Related codes

Full explanation for An 11
Er 01

Your boiler has failed to light the flame needed to heat your home and has safely shut itself down as a precaution.

High Engineer only £120-£250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Ignition lead

Related codes

Full explanation for Er 01
Er 02

Your boiler has detected that it is overheating and has shut itself down to prevent any damage or safety hazards.

High Engineer only £120-250

Parts commonly replaced

  • Limit thermostat
  • Pump (circulator)
  • Primary heat exchanger

Related codes

Full explanation for Er 02
Er 02 + RESET

Your boiler has temporarily shut down because it detected dangerously high internal temperatures, likely due to a blockage or restricted water flow.

Emergency Engineer only £100-250

Parts commonly replaced

  • Safety thermostat
  • Circulating pump
  • Automatic bypass valve
  • Heat exchanger

Related codes

Full explanation for Er 02 + RESET
Er 03

Your boiler has stopped working correctly because the system has encountered a general safety error and has shut itself down to prevent damage.

High Engineer only £120-250

Parts commonly replaced

  • Printed circuit board
  • Wiring harness
  • Ignition transformer

Related codes

Full explanation for Er 03
Er 03 + RESET

Your boiler has temporarily stopped working as a safety precaution and needs a manual reset to try and get going again.

High DIY-safe £90-250

What to check first

  1. Locate the reset button or turn the mode selector to the 'Reset' position on your Biasi boiler control panel.
  2. Hold the reset button down for about 2 to 5 seconds and then release it.
  3. Wait a moment to see if the boiler fires up and resumes normal operation.

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Printed circuit board (PCB)

Related codes

Full explanation for Er 03 + RESET
Er 04

Your boiler is struggling to detect the water flowing through it, which is likely caused by low system pressure.

High DIY-safe £80-180

What to check first

  1. Check your boiler pressure gauge; if it is below 1 bar, find the filling loop (usually a silver braided hose under the boiler).
  2. Open the valves on the filling loop to allow water into the system until the gauge reads 1.5 bar.
  3. Close the valves tightly and restart the boiler.

Parts commonly replaced

  • Circulation pump
  • Flow switch
  • Pressure sensor

Related codes

Full explanation for Er 04
Er 04 +

Your boiler has detected that there is either not enough water in the system or the water isn't moving through the pipes correctly.

High DIY-safe £100-280

What to check first

  1. Check the pressure gauge on the front of the boiler; it should be between 1 and 1.5 bar.
  2. If the pressure is too low, use the filling loop underneath the boiler to top it up with water.
  3. Ensure all radiator valves and isolation valves under the boiler are fully open.

Parts commonly replaced

  • Circulating Pump
  • Water Pressure Switch
  • Flow Temperature Sensor

Related codes

Full explanation for Er 04 +
Er 05

Your boiler has detected an issue with the internal fan that pushes exhaust gases out of your home, so it has safely shut itself down to prevent operation.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Wiring harness
  • Printed Circuit Board (PCB)

Related codes

Full explanation for Er 05
Showing 11–20 of 35
Er 05 +

Your boiler has detected an issue with the internal air circulation system, which is preventing it from igniting safely.

High Engineer only £180-300

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

Full explanation for Er 05 +
Er 06

Your boiler is struggling to accurately measure the temperature of the water used for your radiators, which has caused it to stop working to avoid potential damage.

High Engineer only £120-180

Parts commonly replaced

  • Central Heating NTC Temperature Sensor
  • Wiring harness

Related codes

Full explanation for Er 06
Er 06 +

Your boiler is struggling to accurately measure its own internal water temperature, so it has shut down to prevent overheating.

High Engineer only £120-180

Parts commonly replaced

  • Central Heating NTC Sensor

Related codes

Full explanation for Er 06 +
Er 07

Your boiler is struggling to accurately measure the temperature of the hot water it provides, which has caused it to stop heating your water to prevent overheating.

Medium Engineer only £120-180

Parts commonly replaced

  • DHW NTC thermistor sensor

Related codes

Full explanation for Er 07
Er 07 +

Your boiler is struggling to accurately measure the temperature of the hot water it provides, which has caused it to stop heating your water to prevent overheating.

Medium Engineer only £120-180

Parts commonly replaced

  • DHW NTC thermistor sensor

Related codes

Full explanation for Er 07 +
Er 08

Your boiler is struggling because it has lost the signal from the weather sensor installed outside your home.

Low Engineer only £100-180

Parts commonly replaced

  • External NTC sensor
  • Wiring loom

Related codes

Full explanation for Er 08
Er 08 +

Your boiler is struggling because it has lost the signal from an outdoor thermometer that helps it adjust your heating based on the weather.

Medium Engineer only £120-220

Parts commonly replaced

  • External NTC temperature sensor
  • Wiring harness

Related codes

Full explanation for Er 08 +
Er 09

Your boiler has detected an issue with the sensor that monitors the temperature of the exhaust fumes, meaning the system has shut down as a safety precaution.

High Engineer only £120-220

Parts commonly replaced

  • Flue NTC sensor
  • Wiring harness

Related codes

Full explanation for Er 09
Er 09 +

Your boiler has detected an issue with the sensor that monitors the exhaust gas temperature, causing it to shut down for safety.

High Engineer only £120-220

Parts commonly replaced

  • Flue gas NTC sensor
  • Wiring harness

Related codes

Full explanation for Er 09 +
Er 10

Your boiler has detected that the exhaust gases are getting too hot, so it has safely shut itself down to prevent any damage.

High Engineer only £120-250

Parts commonly replaced

  • Flue sensor
  • NTC sensor
  • Primary heat exchanger

Related codes

Full explanation for Er 10
Showing 21–30 of 35
Er 10 + RESET

Your boiler has automatically shut down because it detected that the exhaust gases from the flue are getting too hot or not flowing away properly.

Emergency Engineer only £150-300

Parts commonly replaced

  • Flue gas sensor
  • Flue assembly
  • Printed Circuit Board (PCB)

Related codes

Full explanation for Er 10 + RESET
Er 11

Your boiler is failing to detect a flame, which means it cannot light safely to provide heating or hot water.

High DIY-safe £100-280

What to check first

  1. Check if other gas appliances (like a hob) are working to ensure gas is reaching the property.
  2. Ensure your gas meter has credit if you use a pre-payment meter.
  3. Gently press the 'Reset' button on the front control panel to see if the boiler restarts.

Parts commonly replaced

  • Ignition Electrode
  • Ionisation Probe
  • Gas Valve
  • Printed Circuit Board (PCB)

Related codes

Full explanation for Er 11
Er 12

Your boiler has sensed a problem with the internal sensor that monitors the temperature of the water returning from your radiators.

Medium Engineer only £90-160

Parts commonly replaced

  • Central heating return NTC thermistor
  • Wiring harness

Related codes

Full explanation for Er 12
Er 12 +

Your boiler has sensed a problem with the internal sensor that monitors the temperature of the water returning from your radiators.

Medium Engineer only £90-160

Parts commonly replaced

  • Central heating return NTC thermistor
  • Wiring harness

Related codes

Full explanation for Er 12 +
Er 13

Your boiler has detected that the water is getting too hot too quickly because it isn't circulating through the system properly.

High DIY-safe £120-£350

What to check first

  1. Check that all radiator valves are fully open
  2. Ensure the boiler pressure is between 1.0 and 1.5 bar
  3. Gently bleed air from your radiators using a radiator key

Parts commonly replaced

  • Circulation Pump
  • Main Heat Exchanger
  • Return Temperature Sensor

Related codes

Full explanation for Er 13
Er 13 +

Your boiler has detected that the water is getting too hot too quickly because it isn't circulating through the system properly.

High DIY-safe £120-£350

What to check first

  1. Check that all radiator valves are fully open
  2. Ensure the boiler pressure is between 1.0 and 1.5 bar
  3. Gently bleed air from your radiators using a radiator key

Parts commonly replaced

  • Circulation Pump
  • Main Heat Exchanger
  • Return Temperature Sensor

Related codes

Full explanation for Er 13 +
Er 14

Your boiler has detected that it is dangerously overheating and has automatically shut down to prevent damage.

High Engineer only £150-300

Parts commonly replaced

  • Central heating pump
  • NTC thermistor
  • Printed Circuit Board
Full explanation for Er 14
Er 14 +

Your boiler has detected that water is not flowing properly through the system fast enough, so it has safely shut down to prevent overheating.

High Engineer only £150-350

Parts commonly replaced

  • Circulating pump
  • Flow sensor
  • Automatic bypass valve

Related codes

Full explanation for Er 14 +
Er 14 + RESET

Your boiler has temporarily stopped working because water inside it has become dangerously hot or the water pump has failed.

Emergency Engineer only £150-350

Parts commonly replaced

  • Central heating pump
  • Primary thermistor
  • Automatic air vent

Related codes

Full explanation for Er 14 + RESET
Er 19

Your boiler is having trouble measuring the temperature of the cold water coming in, which may affect how well it heats your hot water.

Low Engineer only £90-160

Parts commonly replaced

  • DHW inlet temperature probe
  • Connecting wiring harness

Related codes

Full explanation for Er 19
Showing 31–35 of 35
Er 19 +

Your boiler is having trouble measuring the temperature of the cold water coming in, which may affect how well it heats your hot water.

Low Engineer only £90-160

Parts commonly replaced

  • DHW inlet temperature probe
  • Connecting wiring harness

Related codes

Full explanation for Er 19 +
Er 25

Your boiler has temporarily stopped working for safety reasons and needs a professional to investigate the underlying cause.

High Engineer only £150-300

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Printed circuit board (PCB)

Related codes

Full explanation for Er 25
Er 25 + RESET

Your boiler has temporarily locked out because it cannot safely detect a flame inside.

High Engineer only £100-250

Parts commonly replaced

  • Flame sensor electrode
  • Ignition lead
  • Printed Circuit Board (PCB)

Related codes

Full explanation for Er 25 + RESET
Er 69

Your boiler has shut down because it has detected an electrical connection issue or an internal wiring conflict within its control system.

High Engineer only £100-£250

Parts commonly replaced

  • Main PCB
  • Wiring harness
  • External sensor

Related codes

Full explanation for Er 69
Li 01

Your boiler has reached an excessively high temperature while trying to provide hot water and has shut down as a safety precaution.

High Engineer only £120-350

Parts commonly replaced

  • Plate heat exchanger
  • DHW temperature sensor
  • Diverter valve motor
  • Internal pump
Full explanation for Li 01
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