Biasi Basica System 2022 Fault codes & diagnostics

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

System Natural GasLPG 24-28 kW 2022-present

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Severity at a glance

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3 Emergency 20 High 1 Medium 1 Low
Just want the most common Biasi Basica System 2022 faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 25 documented codes

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E01

Your boiler has failed to light the gas flame and has shut down as a safety precaution.

High DIY-safe £90-280

What to check first

  1. Check that your gas emergency control valve is in the 'on' position
  2. Verify that other gas appliances, like a cooker, are working to ensure gas supply
  3. Press the Reset button on the boiler control panel for 2 seconds

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Printed Circuit Board (PCB)

Related codes

Full explanation for E01
E02

Your boiler has shut down because it sensed it was getting too hot, triggering a safety switch to prevent damage.

High DIY-safe £100-220

What to check first

  1. Check that your radiator valves are open and not turned to zero
  2. Ensure there is enough water pressure in the system (typically between 1 and 1.5 bar)
  3. Press the 'Reset' button on the boiler control panel
  4. Check for any obvious obstructions to the external flue pipe

Parts commonly replaced

  • Overheat Thermostat
  • Circulation Pump
  • Thermistor (NTC Sensor)

Related codes

Full explanation for E02
E03

Your boiler's internal computer has encountered a critical error and has stopped working to prevent damage.

High Engineer only £250-£450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

Full explanation for E03
E04

Your boiler has detected that the water pressure is too low or isn't circulating properly, which prevents it from heating up safely.

High DIY-safe £100-£220

What to check first

  1. Locate the pressure gauge on the front of the boiler and check if the needle is below 1.0 bar (typically in the red zone).
  2. Find the internal or external filling loop (braided silver hose) underneath the boiler.
  3. Slowly open the valve(s) until you hear water moving and the pressure gauge rises to 1.5 bar, then close the valves tightly.

Parts commonly replaced

  • Pressure switch
  • Circulation pump
  • Filling loop valve

Related codes

Full explanation for E04
E05

Your boiler has identified a problem with the fan that safely removes exhaust gases, meaning it has stopped working for your safety.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Air pressure switch
  • Main PCB

Related codes

Full explanation for E05
E06

Your boiler's temperature sensor has failed or is giving an incorrect reading, meaning the system cannot safely monitor how hot the water is getting.

High Engineer only £90-160

Parts commonly replaced

  • Main circuit NTC temperature probe
  • Connecting wiring harness

Related codes

Full explanation for E06
E07

Your boiler has detected that a safety sensor in the flue system is either broken or has overheated, causing the unit to shut down for your safety.

High Engineer only £120-220

Parts commonly replaced

  • Flue NTC sensor
  • Safety thermal fuse
  • Wiring harness

Related codes

Full explanation for E07
E08

Your boiler has shut down because the exhaust gases have become too hot, which is a safety measure to prevent damage to the internal components.

High Engineer only £120-£280

Parts commonly replaced

  • Flue NTC Sensor
  • Main Heat Exchanger
  • Circulation Pump

Related codes

Full explanation for E08
E09

Your boiler has detected a problem with the sensor that monitors exhaust gases, and has shut down as a safety precaution.

High Engineer only £120-£200

Parts commonly replaced

  • Flue Gas NTC Sensor
  • Sensor Wiring Loom
  • Main PCB

Related codes

Full explanation for E09
E10

Your boiler has shut down because it detected dangerously high temperatures in the exhaust system, indicating a serious internal overheating issue.

Emergency Engineer only £180-450

Parts commonly replaced

  • Flue gas probe
  • Main heat exchanger
  • Thermal fuse
  • Wiring harness

Related codes

Full explanation for E10
Showing 11–20 of 25
E11

Your boiler thinks a flame is present when there shouldn't be one, causing it to shut down for safety reasons.

High Engineer only £120-300

Parts commonly replaced

  • Ionisation electrode
  • Flame sensing lead
  • Printed Circuit Board (PCB)

Related codes

Full explanation for E11
E12

Your boiler has stopped working because a sensor that monitors the temperature of the water returning to the unit has failed or disconnected.

High Engineer only £90-160

Parts commonly replaced

  • Return NTC thermistor
  • NTC sensor wiring loom

Related codes

Full explanation for E12
E13

Your boiler has too much water inside it, which has caused the system to stop running to protect itself from damage.

Emergency DIY-safe £80-250

What to check first

  1. Check that the filling loop valves (under the boiler) are closed tightly.
  2. Bleed a radiator using a radiator key to release water until the pressure gauge falls back to 1.5 bar.
  3. Reset the boiler once the pressure is back in the green zone.

Parts commonly replaced

  • Filling loop valve
  • Expansion vessel
  • Pressure relief valve

Related codes

Full explanation for E13
E14

Your boiler is heating up too quickly, which usually means the water isn't moving through the system properly.

High DIY-safe £120-£250

What to check first

  1. Check that all radiator valves are fully open
  2. Check that the boiler pressure is between 1.0 and 1.5 bar on the gauge
  3. Bleed your radiators to remove any trapped air

Parts commonly replaced

  • Circulation Pump
  • Flow Temperature Probe (NTC)
  • Main Heat Exchanger (if blocked)

Related codes

Full explanation for E14
E16

Your boiler's main internal computer has developed a fault and can no longer control the heating system correctly.

High Engineer only £250-£450

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

Full explanation for E16
E18

Your boiler has failed to light because it cannot detect a flame or there is a problem with the internal gas delivery system.

High Engineer only £180-450

Parts commonly replaced

  • Gas Valve
  • Ignition Electrode
  • Flame Sensing Electrode
  • Printed Circuit Board (PCB)

Related codes

Full explanation for E18
E21

Your boiler's internal computer boards are having trouble talking to each other, causing the unit to stop working for safety.

High Engineer only £180-450

Parts commonly replaced

  • Main PCB
  • Display PCB
  • Wiring Loom

Related codes

Full explanation for E21
E22

Your boiler is overheating because the water inside is reaching temperatures that are too high for safe operation.

High DIY-safe £120-£350

What to check first

  1. Check that all radiator valves are fully open to allow water to circulate.
  2. Ensure the boiler pressure is between 1.0 and 1.5 bar on the pressure gauge.
  3. Check for any blockages in the system and bleed your radiators to remove trapped air.

Parts commonly replaced

  • Circulation Pump
  • NTC Temperature Sensor
  • Main Heat Exchanger (if scaled)

Related codes

Full explanation for E22
E25

Your boiler has detected that the internal water temperature is very low and has entered a security mode to prevent the pipes from freezing.

Low DIY-safe £0-120

What to check first

  1. Check that the boiler's power supply is switched on
  2. Ensure your thermostat and programmer are calling for heat
  3. Open any radiator valves fully to allow water to circulate
  4. Wait for the boiler to complete its automatic heating cycle to warm the system up

Parts commonly replaced

  • None (Software state)
  • NTC Temperature Sensor

Related codes

Full explanation for E25
E26

Your boiler has detected an internal electrical issue with the valve that controls the gas flow, causing the system to shut down for safety.

High Engineer only £180-280

Parts commonly replaced

  • Gas valve
  • PCB (Main circuit board)
  • Wiring harness

Related codes

Full explanation for E26
Showing 21–25 of 25
E28

Your boiler is struggling to accurately monitor the temperature of your hot water cylinder, which may result in a lack of hot water.

High Engineer only £90-160

Parts commonly replaced

  • Tank NTC thermistor probe
  • Sensor wiring harness

Related codes

Full explanation for E28
E50

Your boiler is having trouble talking to your external smart thermostat or controller, which stops it from receiving heating instructions.

High DIY-safe £90-250

What to check first

  1. Check that your wall thermostat or smart hub is powered on and has working batteries.
  2. Restart your internet router if you are using a Wi-Fi-connected heating system.
  3. Turn the boiler power switch off and back on to refresh the connection.

Parts commonly replaced

  • OpenTherm Receiver
  • Smart Thermostat Batteries
  • Wiring connection
  • Main PCB

Related codes

Full explanation for E50
E52

Your boiler has been locked for security because too many attempts were made to reset it remotely or via an app.

Medium DIY-safe £0-80

What to check first

  1. Locate the physical reset button on the boiler control panel
  2. Press and hold the reset button for at least 5 seconds
  3. Wait for the display to clear and the boiler to restart

Parts commonly replaced

  • None (Software lockout)
  • External Wi-Fi receiver

Related codes

Full explanation for E52
E54

Your boiler has tried to top itself up with water automatically but the pressure is still too low for it to start working.

High DIY-safe £0-120

What to check first

  1. Locate the external filling loop (flexible silver hose) under the boiler.
  2. Slowly open the valve(s) to manually add water while watching the pressure gauge.
  3. Close the valves once the pressure reaches between 1.0 and 1.5 bar.

Parts commonly replaced

  • External filling loop
  • Water pressure sensor
  • Automatic filling valve

Related codes

Full explanation for E54
E58

Your boiler has too much water pressure inside the system after being topped up, which has caused it to lock out for safety.

Emergency DIY-safe £0-120

What to check first

  1. Ensure the blue filling loop taps under the boiler are fully turned off.
  2. Locate a radiator bleed valve and use a key to release water into a cloth or container until the pressure gauge drops to 1.5 bar.
  3. Reset the boiler to clear the error code.

Parts commonly replaced

  • Filling loop valve
  • Pressure sensor

Related codes

Full explanation for E58