Biasi Rinnova Adaptive Combi Fault codes & diagnostics

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

CombiSystem Natural GasLPG 25-35 kW 2021-present
GC Numbers 41-583-3947-583-4647-583-4747-583-48
Download the Biasi Rinnova Adaptive Combi manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

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Severity at a glance

Each cell = one fault code. Hover to identify.
4 Emergency 33 High 1 Medium
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 38 documented codes

Tap any card for details

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 detected an internal issue and has safely shut itself down to prevent damage, meaning you currently have no heating or hot water.

High Engineer only £150-350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Air pressure switch
  • Flue fan

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
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
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
Showing 11–20 of 38
E12

Your boiler is struggling to read the temperature of the water returning to it, so it has safely shut down to prevent overheating.

High Engineer only £120-180

Parts commonly replaced

  • Return NTC Sensor
  • Wiring harness

Related codes

Full explanation for E12
E13

Your boiler is struggling because there is a significant temperature difference between the water leaving the unit and the water returning to it, often indicating a restriction in the flow of water around your system.

High Engineer only £120-250

Parts commonly replaced

  • Central heating pump
  • Diverter valve
  • System filter

Related codes

Full explanation for E13
E14

Your boiler has detected that the water temperature is rising too quickly, suggesting that the pump isn't moving water through the system as it should.

High Engineer only £150-300

Parts commonly replaced

  • Central heating pump
  • Flow sensor
  • System filter

Related codes

Full explanation for E14
E18

Your boiler is failing to detect the expected temperature rise when it tries to start the heating process.

High Engineer only £150-300

Parts commonly replaced

  • NTC temperature sensor
  • Pump
  • Primary heat exchanger

Related codes

Full explanation for E18
E19

Your boiler's control system is struggling to read a signal from one of its internal sensors, which is causing it to stop working as a safety precaution.

High Engineer only £120-250

Parts commonly replaced

  • NTC Sensor
  • Wiring Harness
  • PCB

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 has detected an internal electrical fault with the component that controls the gas supply, meaning it has safely shut itself down to prevent operation.

High Engineer only £200-350

Parts commonly replaced

  • Main PCB
  • Gas Valve

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 has lost the electrical signal required to control the gas flow, so it has safely shut down to prevent incorrect operation.

High Engineer only £150-250

Parts commonly replaced

  • Gas valve modulator
  • Wiring harness
  • Main PCB

Related codes

Full explanation for E23
E24

Your boiler is struggling to breathe because the flue pipe that carries waste gases outside is likely blocked or obstructed.

Emergency Engineer only £120-250

Parts commonly replaced

  • Flue terminal
  • Air pressure switch
  • Fan assembly

Related codes

Full explanation for E24
Showing 21–30 of 38
E25

Your boiler is repeatedly failing to ignite or keep its flame lit, so it has safely shut itself down to prevent a gas buildup.

High Engineer only £150-300

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Flame rectification probe

Related codes

Full explanation for E25
E26

Your boiler has detected a disagreement between its two internal temperature sensors, causing it to shut down for safety reasons.

High Engineer only £120-220

Parts commonly replaced

  • NTC Temperature Sensor
  • Wiring Harness

Related codes

Full explanation for E26
E40

Your boiler is struggling to process the electricity supply correctly, which is preventing it from starting up safely.

High Engineer only £120-250

Parts commonly replaced

  • Printed Circuit Board (PCB)

Related codes

Full explanation for E40
E42

Your boiler's control panel is struggling to register your button presses, likely because the interface board is stuck or faulty.

Medium Engineer only £150-250

Parts commonly replaced

  • User interface control board
  • Front panel membrane

Related codes

Full explanation for E42
E44

Your boiler is failing to ignite because it cannot detect a flame after trying to start, which means you currently have no heating or hot water.

High Engineer only £150-350

Parts commonly replaced

  • Gas valve
  • Ignition electrode
  • PCB

Related codes

Full explanation for E44
E50

Your boiler is having trouble communicating with your thermostat, which is preventing it from receiving instructions on when to turn on the heating or hot water.

High Engineer only £120-250

Parts commonly replaced

  • OpenTherm controller unit
  • PCB
  • Wiring loom

Related codes

Full explanation for E50
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 is struggling to receive enough gas to ignite properly, which has caused it to stop working to keep your home safe.

High Engineer only £120-250

Parts commonly replaced

  • Gas valve
  • Gas meter regulator
  • Gas supply pipework

Related codes

Full explanation for E68
E77

Your boiler's internal computer is experiencing a communication error with its gas control system, meaning it cannot safely regulate the flame.

High Engineer only £150-300

Parts commonly replaced

  • Gas valve
  • PCB (Printed Circuit Board)

Related codes

Full explanation for E77
Showing 31–38 of 38
E78

Your boiler is struggling to receive enough gas to ignite properly, which has caused it to shut down for safety reasons.

Emergency Engineer only £120-250

Parts commonly replaced

  • Gas valve
  • Gas meter regulator
  • Gas pipework seals

Related codes

Full explanation for E78
E79

Your boiler's internal computer is experiencing a communication error with its gas control system, preventing it from safely regulating the flame.

High Engineer only £150-300

Parts commonly replaced

  • PCB (Printed Circuit Board)
  • Gas Valve

Related codes

Full explanation for E79
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

The boiler's main control computer is not correctly set up to operate your specific heating system.

High Engineer only £150-300

Parts commonly replaced

  • Main printed circuit board (PCB)
  • Configuration plug

Related codes

Full explanation for E99
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
Status & diagnostic codes

8 operating states & engineer diagnostics

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

bP Status Your boiler has detected very low temperatures and is automatically warming itself up to prevent the internal pipes from freezing. cP Diagnostic Your boiler is currently running at its maximum power for a performance test and is not experiencing a breakdown. dP Diagnostic Your boiler is currently running at its maximum power setting for a performance test or service check. hP Diagnostic 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. L01 Status Your boiler is overheating while trying to provide hot water, causing it to shut down to protect itself. LP Diagnostic Your boiler is currently running in a special test mode used by engineers to check performance and is not experiencing an actual hardware fault. PO Status Your boiler is simply finishing a standard cooling cycle and is not currently experiencing a breakdown. Wrench symbol Diagnostic Your boiler is notifying you that it is due for its routine annual service to keep it running safely and efficiently.
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