Biasi Inovia 35C Fault codes & diagnostics

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

Combi Natural Gas 2012-present
GC Number 47-583-34
Download the Biasi Inovia 35C 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.
1 Emergency 31 High 5 Medium 2 Low
Fault codes

All 39 documented codes

Tap any card for details

An

Your boiler is struggling to light or detect a steady flame, which means it has shut down as a safety precaution.

High DIY-safe £90-280

What to check first

  1. Check that your gas supply is turned on and other gas appliances are working
  2. Press and hold the 'R' Reset button for 2-3 seconds to restart the ignition sequence
  3. Ensure the condensate pipe (outside white plastic pipe) isn't frozen if it is currently cold weather

Parts commonly replaced

  • Ionisation Electrode
  • Ignition Lead
  • Gas Valve
  • Printed Circuit Board (PCB)
Full explanation for An
E01

Your boiler has failed to light the flame, which means it has shut down for safety to prevent gas from flowing without being burned.

High DIY-safe £100-350

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. Press and hold the 'Reset' button for 2-3 seconds to see if the boiler restarts

Parts commonly replaced

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

Related codes

Full explanation for E01
E02

Your boiler has got too hot and has automatically shut down for safety to prevent internal damage.

High DIY-safe £90-250

What to check first

  1. Check that all radiator valves are open to allow water to flow.
  2. Ensure there is enough pressure in the system (between 1 and 1.5 bar).
  3. Turn the selector switch to 'Reset' for 5 seconds and then back to its original position.

Parts commonly replaced

  • Safety Thermostat (Overheat Limit)
  • Circulation Pump
  • Heat Exchanger

Related codes

Full explanation for E02
E03

Your boiler has stopped working because it cannot properly clear away the combustion gases, likely due to a flue blockage or a problem with the fan.

High Engineer only £150-250

Parts commonly replaced

  • Flue fan
  • Air pressure switch
  • Venturi

Related codes

Full explanation for E03
E04

Your boiler has detected that there is not enough water pressure or flow to operate safely and has stopped working as a result.

High DIY-safe £0-250

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 up the water.
  3. Ensure all radiator valves and isolation valves are fully open.
  4. Restart the boiler once the correct pressure is reached.

Parts commonly replaced

  • Filling loop
  • Water pressure switch
  • Circulation pump

Related codes

Full explanation for E04
E04 +

Your boiler has stopped working because the water pressure is too low for it to run safely.

High DIY-safe £80-160

What to check first

  1. Locate the filling loop (usually a silver flexible hose) underneath the boiler.
  2. Slowly open the valves until you hear water flowing and the pressure gauge reaches between 1 and 1.5 bar.
  3. Close both valves tightly and restart the boiler.

Parts commonly replaced

  • Pressure transducer
  • Filling loop valve

Related codes

Full explanation for E04 +
E05

Your boiler has stopped working because the fan that helps remove waste gases is not spinning at the correct speed or communicating properly with the control board.

High Engineer only £220-£450

Parts commonly replaced

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

Related codes

Full explanation for E05
E05 +

Your boiler has detected a problem with the fan that clears away waste gases, causing the system to shut down for safety.

High Engineer only £180-350

Parts commonly replaced

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

Related codes

Full explanation for E05 +
E06

Your boiler's internal sensor that monitors the temperature of the water for your radiators has developed a fault, meaning the system cannot heat your home safely.

High Engineer only £90-160

Parts commonly replaced

  • C.H. Flow NTC Temperature Probe
  • Wiring harness / Connector

Related codes

Full explanation for E06
E06 +

Your boiler is struggling to accurately measure its own temperature, meaning your central heating may not heat up reliably or could cut out entirely.

High Engineer only £90-160

Parts commonly replaced

  • NTC Temperature Probe
  • Wiring Harness

Related codes

Full explanation for E06 +
Showing 11–20 of 39
E07

Your boiler has detected a problem with the sensor that monitors the water temperature returning from your radiators, causing the system to stop working for safety.

High Engineer only £90-160

Parts commonly replaced

  • Return NTC thermistor
  • NTC sensor wiring harness

Related codes

Full explanation for E07
E07 +

Your boiler is struggling to accurately measure the temperature of the water coming out of your hot taps, which usually means your hot water won't reach the right temperature or may not work at all.

Medium Engineer only £90-160

Parts commonly replaced

  • Domestic Hot Water (DHW) NTC Thermistor
  • Connecting wiring harness

Related codes

Full explanation for E07 +
E08

Your boiler is having trouble reading the temperature outside, which may cause your heating to respond incorrectly to weather changes.

Low Engineer only £90-160

Parts commonly replaced

  • External temperature sensor (NTC)
  • Sensor wiring harness

Related codes

Full explanation for E08
E08 +

Your boiler has lost connection with its outdoor temperature sensor, which helps it adjust the heating based on the weather.

Low Engineer only £90-160

Parts commonly replaced

  • External Temperature NTC Probe
  • External Sensor Wiring

Related codes

Full explanation for E08 +
E09

Your boiler has detected that a temperature sensor in the flue has stopped working correctly, which has caused the system to shut down for safety.

High Engineer only £120-£200

Parts commonly replaced

  • Flue temperature probe (NTC)
  • Wiring harness connectors

Related codes

Full explanation for E09
E09 +

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

High Engineer only £120-£190

Parts commonly replaced

  • Flue NTC Temperature Sensor
  • Wiring Harness

Related codes

Full explanation for E09 +
E10

Your boiler has shut down because a sensor detected that the exhaust gases are becoming 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
  • Printed Circuit Board (PCB)

Related codes

Full explanation for E10
E12

Your boiler has detected that a sensor responsible for monitoring the temperature of the water returning from your radiators has developed a fault, preventing the system from operating correctly.

High Engineer only £90-£160

Parts commonly replaced

  • Central heating return NTC thermistor
  • Sensor wiring harness

Related codes

Full explanation for E12
E12 +

Your boiler has detected a problem with the sensor that monitors the temperature of the water returning to the unit, causing it to shut down for safety.

High Engineer only £90-160

Parts commonly replaced

  • Return NTC thermistor (temperature probe)
  • Wiring harness connecting the probe

Related codes

Full explanation for E12 +
E13

Your boiler is overheating because the water is not circulating quickly enough between the internal pipes.

High DIY-safe £120-£350

What to check first

  1. Check that your silver central heating valves under the boiler are fully open
  2. Ensure all radiator valves (TRVs) are turned to the highest setting
  3. Check the boiler pressure is between 1 and 1.5 bar on the gauge
  4. Bleed all radiators to remove trapped air

Parts commonly replaced

  • Circulation Pump
  • Main Heat Exchanger (Descaling)
  • Flow/Return Thermistors

Related codes

Full explanation for E13
Showing 21–30 of 39
E13 +

Your boiler has detected that the water is heating up too quickly or not circulating properly, causing it to shut down to prevent overheating.

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. Bleed all radiators to remove trapped air bubbles
  4. Reset the boiler using the control dial

Parts commonly replaced

  • Circulation pump
  • Main heat exchanger
  • Central heating filter

Related codes

Full explanation for E13 +
E14

Your boiler has stopped working because the water isn't moving through the system properly, causing it to overheat.

High DIY-safe £180-350

What to check first

  1. Check that your boiler pressure is between 1 and 1.5 bar on the gauge
  2. Ensure all radiator valves and isolation valves under the boiler are fully open
  3. Gently bleed your radiators to remove any trapped air pockets

Parts commonly replaced

  • Central heating pump
  • Main heat exchanger
  • Primary thermistor (NTC sensor)

Related codes

Full explanation for E14
E14 +

Your boiler has detected that water is heating up too quickly because it isn't moving through the system properly.

High DIY-safe £120-£350

What to check first

  1. Check that the boiler pressure is between 1.0 and 1.5 bar
  2. Ensure all radiator valves and external isolation valves are fully open
  3. Gently bleed your radiators to remove any trapped air pockets

Parts commonly replaced

  • Circulation Pump
  • Main Heat Exchanger
  • Flow/Return Temperature Sensors

Related codes

Full explanation for E14 +
E19

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

Medium Engineer only £90-160

Parts commonly replaced

  • DHW Inlet NTC Thermistor
  • Wiring Harness

Related codes

Full explanation for E19
E19 +

Your boiler is struggling to accurately measure the temperature of the water entering the system, which can cause inconsistent hot water temperatures.

Medium Engineer only £90-160

Parts commonly replaced

  • Domestic Hot Water (DHW) Inlet NTC Sensor
  • Sensor Wiring Harness

Related codes

Full explanation for E19 +
E20

Your boiler has stopped working because it cannot safely detect or ignite a flame, resulting in a total lockout for safety reasons.

High Engineer only £180-350

Parts commonly replaced

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

Related codes

Full explanation for E20
E21

Your boiler has stopped working because it failed to ignite or check the gas flow properly for safety reasons.

High Engineer only £180-450

Parts commonly replaced

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

Related codes

Full explanation for E21
E22

Your boiler has detected an issue with the gas valve or the electrical supply to it, preventing the burner from igniting to keep your home warm.

High Engineer only £150-300

Parts commonly replaced

  • Gas valve
  • Wiring harness
  • PCB

Related codes

Full explanation for E22
E23

Your boiler has stopped working because it cannot safely ignite the gas or maintain a flame.

High Engineer only £150-£350

Parts commonly replaced

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

Related codes

Full explanation for E23
E24

Your boiler has failed to light the flame safely, so it has locked itself out to prevent gas from escaping.

High Engineer only £120-250

Parts commonly replaced

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

Related codes

Full explanation for E24
Showing 31–39 of 39
E25

Your boiler has detected an issue with the burning process and has shut itself down as a safety precaution to prevent unsafe operation.

Emergency Engineer only £150-300

Parts commonly replaced

  • Flue fan
  • Air pressure switch
  • Ignition electrode
  • Gas valve

Related codes

Full explanation for E25
E44

Your boiler is having trouble controlling the flame brightness, which usually means the internal gas control system has stopped working correctly to keep you safe.

High Engineer only £180-350

Parts commonly replaced

  • Gas Valve
  • Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

Full explanation for E44
E50

Your boiler has lost its connection to the thermostat or controller that manages the second heating zone in your home.

Medium DIY-safe £60-180

What to check first

  1. Check if the batteries in your Zone 2 room thermostat need replacing
  2. Ensure the remote control or thermostat is within range of the boiler
  3. Check for any wireless interference from other electronic devices near the receiver

Parts commonly replaced

  • Batteries
  • Wireless Receiver
  • Zone 2 Thermostat
Full explanation for E50
E69

Your boiler has stopped working because it has detected a problem with its internal electrical connections or wiring.

High Engineer only £90-250

Parts commonly replaced

  • Main PCB
  • Wiring Harness
  • Ignition Transformer

Related codes

Full explanation for E69
E69 +

Your boiler has detected an internal electrical communication problem or a wiring mistake that is preventing it from starting up safely.

High Engineer only £100-250

Parts commonly replaced

  • Main PCB (Circuit Board)
  • Wiring Harness
  • Display PCB

Related codes

Full explanation for E69 +
E98

Your boiler is having trouble communicating with the solar panel control system, which means your renewable energy setup isn't working correctly with your heating.

Medium Engineer only £150-£350

Parts commonly replaced

  • Solar control module
  • Printed Circuit Board (PCB)
  • Communication wiring

Related codes

Full explanation for E98
E99

Your boiler's internal computer has lost its settings and doesn't know which model it is supposed to be operating as.

High Engineer only £80-160

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • External Software Key

Related codes

Full explanation for E99
E99 +

Your boiler’s internal computer has forgotten its settings and does not know which model it is supposed to be, causing it to stop working entirely.

High Engineer only £90-250

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Parameter configuration key

Related codes

Full explanation for E99 +
Er 99

Your boiler’s internal computer has forgotten which model it is, meaning it has lost its configuration settings and cannot operate.

High Engineer only £80-160

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
Full explanation for Er 99
Status & diagnostic codes

5 operating states & engineer diagnostics

Not faults — these are normal operating states. Tap to expand.

cP Diagnostic Your boiler is currently running at its highest power setting for a professional combustion test and should return to normal operation automatically after a short period. dP Diagnostic Your boiler is currently running a manual test mode to check the flue and emissions, and it's not actually broken. hp Diagnostic Your boiler is currently running a maintenance test mode used by engineers to check emission levels at low power. L 01 Status Your boiler has shut down because it is getting too hot while trying to provide hot water. LP Diagnostic Your boiler is currently running in a specialist service mode used by engineers to test the system at its lowest power setting.
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