Biasi Rinnova Adaptive Combi Fault codes & diagnostics

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

Combi Natural GasLPG 25-35 kW 2021-present

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Severity at a glance

Each cell = one fault code. Hover to identify.
4 Emergency 52 High 2 Medium 7 Low
Just want the most common Biasi Rinnova Adaptive Combi faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 65 documented codes

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bP

Your boiler has detected very low temperatures and is automatically warming itself up to prevent the internal pipes from freezing.

Low DIY-safe £0

What to check first

  1. Wait for the boiler to finish its warming cycle; the code will disappear once it reaches a safe temperature.
  2. Ensure your household heating is turned on or the thermostat is turned up to keep the system warm.
  3. Check that any visible external condensate pipes are not frozen or blocked with ice.
Full explanation for bP
cP

Your boiler is currently running at its maximum power for a performance test and is not experiencing a breakdown.

Low DIY-safe £0

What to check first

  1. Wait for the 15-minute test timer to expire automatically
  2. Press the Reset or Mode button to manually exit the test mode
  3. Turn the heating or hot water dials slightly to see if the display reverts to the temperature
Full explanation for cP
dP

Your boiler is currently running at its maximum power setting for a performance test or service check.

Low DIY-safe £0

What to check first

  1. Turn the selector knob back to the 'On' or 'Auto' position
  2. Wait up to 15 minutes for the test cycle to automatically time out
  3. Restart the boiler to exit the service mode
Full explanation for dP
E01

Your boiler is failing to light the gas or cannot detect that a flame has been successfully started.

High DIY-safe £100-350

What to check first

  1. Check if other gas appliances in your home, like a hob, are working to ensure gas supply.
  2. Ensure your gas meter has credit and the isolation valve is open.
  3. Press and hold the 'R' Reset button for 2-3 seconds to see if the boiler restarts.

Parts commonly replaced

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

Related codes

Full explanation for E01
E02

Your boiler has detected that it is getting too hot and has automatically shut down to prevent damage or safety issues.

High DIY-safe £100-280

What to check first

  1. Check that your radiator valves are open and not turned to zero.
  2. Verify that the boiler pressure gauge is between 1 and 1.5 bar; top up if necessary.
  3. Try resetting the boiler by turning the control knob to the 'R' position for a few seconds.

Parts commonly replaced

  • Overheat Thermostat
  • Central Heating Pump
  • Main Heat Exchanger (Cleaning or Replacement)

Related codes

Full explanation for E02
E03

Your boiler has shut down because it detected that the exhaust gases are getting too hot or a safety fuse has blown to prevent heat damage.

High Engineer only £120-£250

Parts commonly replaced

  • Flue NTC sensor
  • Thermal fuse
  • Heat exchanger cleaning

Related codes

Full explanation for E03
E04

Your boiler has detected that the water pressure is too low for it to operate safely and has shut itself down.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (usually a silver flexible hose) underneath the boiler.
  2. Slowly open the one or two small taps on the hose until you hear water moving.
  3. Watch the pressure gauge until it reaches between 1.0 and 1.5 bar, then close the taps tightly.

Parts commonly replaced

  • Filling loop
  • Pressure sensor
  • Expansion vessel

Related codes

Full explanation for E04
E05

Your boiler has safety-locked itself because it is having trouble detecting or maintaining a flame.

High DIY-safe £100-£250

What to check first

  1. Check that your gas pre-payment meter has credit (if applicable)
  2. Check that other gas appliances in your home, like a hob, are working correctly
  3. Press and hold the 'Reset' button for five seconds to attempt to restart the boiler

Parts commonly replaced

  • Ignition electrode
  • Flame sensing electrode
  • Gas valve

Related codes

Full explanation for E05
E06

Your boiler has detected a problem with the sensor that monitors the temperature of the water being sent to your radiators, which prevents the heating from running safely.

High Engineer only £90-160

Parts commonly replaced

  • Central Heating Flow NTC Sensor
  • Sensor Wiring Harness

Related codes

Full explanation for E06
E07

Your boiler's temperature sensor for your hot water has stopped working correctly, meaning your taps may only run cold or the temperature will be inconsistent.

High Engineer only £90-160

Parts commonly replaced

  • DHW NTC Temperature Probe
  • Wiring Harness Connection

Related codes

Full explanation for E07
Showing 11–20 of 65
E08

Your boiler has detected a problem with the sensor that monitors the temperature of the water returning from your radiators, which prevents it from operating safely.

High Engineer only £90-160

Parts commonly replaced

  • Return NTC thermistor sensor
  • Wiring harness

Related codes

Full explanation for E08
E09

Your boiler has detected a problem with the sensor that monitors the temperature of the exhaust gases, causing the system to shut down for safety.

High Engineer only £120-£200

Parts commonly replaced

  • Flue NTC sensor
  • Sensor wiring harness
  • Main PCB

Related codes

Full explanation for E09
E10

Your boiler has shut down because it has detected dangerously high temperatures within the exhaust flue system.

Emergency Engineer only £180-350

Parts commonly replaced

  • Flue gas probe
  • Thermal fuse
  • Heat exchanger cleaning
  • Main PCB

Related codes

Full explanation for E10
E11

Your boiler has detected a flame when it shouldn't be there, causing the system to lock out for safety.

High Engineer only £120-280

Parts commonly replaced

  • Flame sense electrode
  • Gas valve
  • Main PCB

Related codes

Full explanation for E11
E12

Your boiler is struggling to ignite because it either isn't receiving enough gas or there is a communication problem within its internal control board.

High DIY-safe £180-450

What to check first

  1. Check that your gas meter has credit and the isolation valve is open
  2. Check if other gas appliances, like a hob, are working correctly
  3. Press and hold the 'Reset' button for five seconds to restart the ignition sequence

Parts commonly replaced

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

Related codes

Full explanation for E12
E13

Your boiler is failing to light the fuel or recognize that a flame has started, meaning you likely have no heating or hot water.

High DIY-safe £120-450

What to check first

  1. Check that your gas supply is turned on at the meter
  2. Check if other gas appliances (like a hob) are working
  3. Press and hold the 'Reset' button for five seconds to restart the ignition sequence

Parts commonly replaced

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

Related codes

Full explanation for E13
E14

Your boiler is having trouble lighting the gas or confirming that a flame has started, so it has shut down for safety.

High Engineer only £120-£350

Parts commonly replaced

  • Ignition electrode
  • Detection electrode
  • Main electronic PCB
  • Ignition lead

Related codes

Full explanation for E14
E15

Your boiler has sensed that the water returning from your radiators is hotter than the water leaving the boiler, which usually means the water isn't flowing through the system correctly.

High DIY-safe £120-280

What to check first

  1. Check that all radiator valves are fully open
  2. Ensure the boiler pressure is between 1 and 1.5 bar on the gauge
  3. Reset the boiler using the control knob to see if the error clears

Parts commonly replaced

  • NTC Temperature Sensor
  • Circulation Pump
  • Main PCB

Related codes

Full explanation for E15
E16

Your boiler's fan is spinning faster than it should, which has caused the system to shut down for safety.

High Engineer only £250-450

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Venturi tube

Related codes

Full explanation for E16
E17

Your boiler has identified a communication problem with the fan that safely removes exhaust gases, causing the system to shut down for safety.

High Engineer only £180-380

Parts commonly replaced

  • Fan assembly
  • Wiring harness
  • Main PCB

Related codes

Full explanation for E17
Showing 21–30 of 65
E18

Your boiler is struggling to light or detect a flame, which means it cannot safely heat your water or radiators.

High DIY-safe £120-£350

What to check first

  1. Check that your gas emergency control valve is in the 'on' position.
  2. Verify if other gas appliances (like a hob) are working to ensure there is a gas supply.
  3. Reset the boiler by turning the control knob to the 'R' position for 5 seconds and then back to 'On'.

Parts commonly replaced

  • Ignition Electrode
  • Flame Detection Electrode
  • Main PCB (Printed Circuit Board)

Related codes

Full explanation for E18
E19

Your boiler has failed to set itself up correctly to handle the gas supply and cannot safely ignite to provide heating or hot water.

High Engineer only £120-£350

Parts commonly replaced

  • Gas valve
  • Main PCB
  • Ignition electrode

Related codes

Full explanation for E19
E20

Your boiler's control system has detected a critical electrical failure within the gas valve mechanism, preventing it from firing for safety reasons.

High Engineer only £180-£350

Parts commonly replaced

  • Gas Valve
  • Main PCB (Control Board)
  • Wiring Harness

Related codes

Full explanation for E20
E21

Your boiler's internal computer has encountered a communication glitch and cannot send or receive the signals needed to run properly.

High Engineer only £250-£450

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
  • Wiring Harness

Related codes

Full explanation for E21
E22

Your boiler has detected a flame that continues to burn even after the gas valve should have closed, which is a safety lockout to prevent uncontrolled burning.

Emergency Engineer only £180-350

Parts commonly replaced

  • Gas Valve
  • Spark/Ionisation Electrode
  • Printed Circuit Board (PCB)

Related codes

Full explanation for E22
E23

Your boiler's internal computer brain is having trouble communicating or has lost power, meaning the system cannot safely operate your heating or hot water.

High Engineer only £180-450

Parts commonly replaced

  • Main PCB
  • Internal Glass Fuses
  • Wiring Harness

Related codes

Full explanation for E23
E24

Your boiler has detected a sequence error or a stuck internal part, which means it cannot properly switch between providing heating and hot water.

High Engineer only £140-£350

Parts commonly replaced

  • Diverter valve motor
  • Main PCB
  • DHW flow switch

Related codes

Full explanation for E24
E25

Your boiler has detected a conflict where it is getting too hot internally, likely because water is stuck or the sensors are sending conflicting information to the brains of the unit.

High Engineer only £120-380

Parts commonly replaced

  • Main PCB
  • Diverter Valve Motor
  • DHW Flow Switch

Related codes

Full explanation for E25
E26

Your boiler has detected an internal communication error or a sensor failure, meaning it cannot accurately measure the temperature of the water used for your heating or taps.

High Engineer only £120-£350

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • NTC Temperature Sensor
  • Wiring Harness

Related codes

Full explanation for E26
E30

Your boiler is struggling to get a steady gas supply or there is a communication issue with its main control board, meaning it cannot ignite safely.

High DIY-safe £120-£450

What to check first

  1. Check that your gas emergency control valve is in the 'on' position
  2. If you have a pre-payment meter, ensure you have sufficient credit
  3. Press and hold the 'Reset' button for 5 seconds to clear the fault

Parts commonly replaced

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

Related codes

Full explanation for E30
Showing 31–40 of 65
E32

Your boiler has detected a problem with the sensor that monitors your hot water temperature or the control board that talks to it.

Medium Engineer only £90-180

Parts commonly replaced

  • DHW Temperature NTC Probe
  • Wiring Harness
  • Main Printed Circuit Board (P.C.B.)

Related codes

Full explanation for E32
E40

Your boiler is struggling to ignite or stay lit because it cannot get the right balance of gas and air needed for a safe flame.

High Engineer only £120-£350

Parts commonly replaced

  • Gas valve
  • Fan
  • Flue seals
  • Air restrictor

Related codes

Full explanation for E40
E42

Your boiler is having trouble breathing or receiving gas, meaning it cannot safely light the flame to provide heating or hot water.

High Engineer only £120-350

Parts commonly replaced

  • Fan
  • Gas Valve
  • Air Pressure Switch
  • Flue Seals

Related codes

Full explanation for E42
E44

Your boiler is failing to light the gas or keep the flame burning, which means your heating and hot water have stopped working.

High DIY-safe £100-£350

What to check first

  1. Check if other gas appliances, like a cooker, are working to ensure gas is reaching your home.
  2. Verify that your gas meter has credit and the isolation valve is open.
  3. Press the Reset button on the boiler control panel once to see if the system restarts.

Parts commonly replaced

  • Ignition Electrode
  • Gas Valve
  • Main Electronic PCB

Related codes

Full explanation for E44
E45

Your boiler is struggling to keep its flame lit while it tries to automatically adjust itself for efficient burning.

High Engineer only £120-£280

Parts commonly replaced

  • Ionisation electrode
  • Spark electrode
  • Gas valve
  • PCB

Related codes

Full explanation for E45
E46

Your boiler is struggling to keep its flame lit while it tries to automatically adjust itself for efficient operation.

High DIY-safe £120-350

What to check first

  1. Check that your external gas meter has credit (if on a prepay meter)
  2. Verify that other gas appliances in your home, like a hob, are working correctly
  3. Press and hold the 'Reset' button for five seconds to allow the boiler to restart its setup process

Parts commonly replaced

  • Flame sensing electrode
  • Gas valve
  • Ignition lead

Related codes

Full explanation for E46
E48

Your boiler is failing to start up because it cannot correctly adjust its internal settings to run at a low power level.

High Engineer only £120-280

Parts commonly replaced

  • Gas Valve
  • Electrode
  • PCB

Related codes

Full explanation for E48
E49

Your boiler has detected that the gas is not burning correctly, which means it has shut down to prevent inefficient or unsafe operation.

High Engineer only £120-£350

Parts commonly replaced

  • Ionisation electrode
  • Gas valve
  • Burner
  • Flue seals

Related codes

Full explanation for E49
E50

Your boiler has detected a temperature sensor problem or a blockage that is preventing your hot water and heating from reaching the correct temperature.

High Engineer only £100-£250

Parts commonly replaced

  • Main circuit NTC thermistor
  • DHW heat exchanger
  • DHW temperature probe

Related codes

Full explanation for E50
E52

Your boiler has detected that exhaust fumes are not escaping correctly through the flue pipe or are being sucked back into the unit, causing it to shut down for safety.

Emergency Engineer only £120-350

Parts commonly replaced

  • Flue seals
  • Fan assembly
  • Venturi tube
  • Air pressure switch

Related codes

Full explanation for E52
Showing 41–50 of 65
E62

Your boiler is requesting a technical adjustment to its internal gas settings to ensure it burns fuel efficiently and safely.

High Engineer only £80-160

Parts commonly replaced

  • Gas Valve
  • Electrode
  • Control Board

Related codes

Full explanation for E62
E65

Your boiler is struggling to maintain a safe and stable flame, causing it to shut down for safety.

High Engineer only £120-350

Parts commonly replaced

  • Ionisation electrode
  • Gas valve
  • PCB (Main circuit board)

Related codes

Full explanation for E65
E68

Your boiler has detected an issue with how it manages water pressure or measures the outside temperature, which may cause it to stop working for safety.

Medium Engineer only £90-250

Parts commonly replaced

  • Expansion Vessel
  • Safety Relief Valve
  • External Temperature Probe
  • Pressure Gauge

Related codes

Full explanation for E68
E69

Your boiler's computer has detected an internal communication or electrical wiring fault, preventing the system from operating safely.

High Engineer only £180-£450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Internal Wiring Harness

Related codes

Full explanation for E69
E70

Your boiler is struggling to light or cannot confirm a flame is present, meaning it has locked itself out for safety.

High Engineer only £120-220

Parts commonly replaced

  • Ignition Electrode
  • Flame Detection Probe
  • Ignition Lead
  • Gas Valve

Related codes

Full explanation for E70
E73

Your boiler has stopped working because one of its internal sensors is sending incorrect information while the system tries to perform an automatic self-check.

High Engineer only £120-220

Parts commonly replaced

  • Heating Flow NTC Probe
  • Return NTC Probe
  • Flue Gas Sensor
  • DHW Probe

Related codes

Full explanation for E73
E74

Your boiler is struggling to detect a rise in temperature while trying to set itself up, which usually means the water isn't moving through the system properly.

High DIY-safe £120-280

What to check first

  1. Check that the boiler pressure is between 1.0 and 1.5 bar
  2. Ensure all radiator valves and isolation valves under the boiler are fully open
  3. Reset the boiler to see if the calibration process completes on the second attempt

Parts commonly replaced

  • Circulation Pump
  • Temperature NTC Sensor
  • Heat Exchanger (Cleaning or Replacement)

Related codes

Full explanation for E74
E75

Your boiler has detected an unsafe level of combustion gases and has shut down as a safety precaution before it can adjust its settings.

Emergency Engineer only £120-350

Parts commonly replaced

  • Gas valve
  • Flame sensing electrode
  • Main PCB
  • Burner gasket

Related codes

Full explanation for E75
E76

Your boiler is detecting a flame when there shouldn't be one, and as a safety precaution, it has stopped the ignition process.

High Engineer only £120-£350

Parts commonly replaced

  • Ionisation electrode
  • Gas valve
  • Main PCB

Related codes

Full explanation for E76
E77

Your boiler has detected an electrical issue with its main control board or incoming power supply, preventing it from operating safely.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
  • Power supply cable

Related codes

Full explanation for E77
Showing 51–60 of 65
E78

Your boiler has detected an internal electrical supply problem or a failure within its main control board, meaning it cannot operate safely.

High Engineer only £250-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Voltage Regulator

Related codes

Full explanation for E78
E79

Your boiler is experiencing a critical communication or electrical supply issue within its internal control board.

High Engineer only £280-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Electrical wiring harness

Related codes

Full explanation for E79
E80

Your boiler has detected a communication failure or an electrical fault between its central controller and the gas control system, preventing it from firing up safely.

High Engineer only £250-£480

Parts commonly replaced

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

Related codes

Full explanation for E80
E85

Your boiler's main control board has detected an electrical fault or an unstable power supply, preventing the unit from operating safely.

High Engineer only £280-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Voltage Regulator

Related codes

Full explanation for E85
E89

Your boiler has detected an issue with its internal computer board or the electrical power being supplied to it.

High DIY-safe £250-450

What to check first

  1. Turn the boiler power off at the fused spur switch
  2. Wait for 60 seconds
  3. Turn the power back on and press the Reset button

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Surge Protector

Related codes

Full explanation for E89
E91

Your boiler has shut down permanently because it tried and failed to restart itself too many times after a recurring technical fault.

High Engineer only £100-350

Parts commonly replaced

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

Related codes

Full explanation for E91
E96

Your boiler has detected an issue with the electrical power supply coming into your home, meaning the frequency is outside of the safe range required for it to operate.

High Engineer only £120-450

Parts commonly replaced

  • Main Control PCB
  • Voltage Stabiliser

Related codes

Full explanation for E96
E97

Your boiler is not receiving enough electrical power from the mains supply to operate safely and has shut down as a precaution.

High Engineer only £100-£350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • External Voltage Regulator

Related codes

Full explanation for E97
E99

Your boiler’s internal computer has suffered a major failure and can no longer control the heating or hot water operations.

High Engineer only £280-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)

Related codes

Full explanation for E99
hP

Your boiler is currently running a manual test mode to check its performance at the lowest power setting and is not experiencing a functional fault.

Low DIY-safe £0

What to check first

  1. Wait for the chimney sweep test to finish automatically (usually takes 15 minutes)
  2. Press the 'Reset' or 'Mode' button to manually exit the test mode
  3. Turn the power off and back on again if the code persists

Related codes

Full explanation for hP
Showing 61–65 of 65
L1

Your boiler has detected that water is not circulating correctly through the system, which is preventing it from heating up safely.

High DIY-safe £120-£350

What to check first

  1. Check the pressure gauge on the front of the boiler and ensure it is between 1.0 and 1.5 bar.
  2. If the pressure is too low, use the filling loop underneath the boiler to top it up.
  3. Ensure all radiator valves are open and that the pump is not making any unusual grinding noises.
  4. Reset the boiler by turning the selector switch to the 'R' position for a few seconds.

Parts commonly replaced

  • Circulation Pump
  • Main Circuit Pressure Switch
  • Main PCB

Related codes

Full explanation for L1
L01

Your boiler is overheating while trying to provide hot water, causing it to shut down to protect itself.

High Engineer only £120-£350

Parts commonly replaced

  • Plate Heat Exchanger
  • DHW Temperature Sensor (NTC)
  • Diverter Valve Motor

Related codes

Full explanation for L01
LP

Your boiler is currently running in a special test mode used by engineers to check performance and is not experiencing an actual hardware fault.

Low DIY-safe £0

What to check first

  1. Locate the selector or reset dial on the front panel.
  2. Turn the dial away from the chimney sweep or 'test' position back to your desired heating or hot water setting.
  3. Wait a few seconds for the 'LP' code to disappear and the screen to return to normal temperature display.

Related codes

Full explanation for LP
PO

Your boiler is simply finishing a standard cooling cycle and is not currently experiencing a breakdown.

Low DIY-safe £0

What to check first

  1. Wait for the boiler to finish circulating water (usually 1-5 minutes).
  2. Monitor the display until the PO code disappears and the temperature returns to normal.
  3. No further action is required as this is normal operation.
Full explanation for PO
Wrench symbol

Your boiler is notifying you that it is due for its routine annual service to keep it running safely and efficiently.

Low Engineer only £80-£120

Parts commonly replaced

  • Service kit
  • Burner gasket
  • Electrode
Full explanation for Wrench symbol