Remeha Avanta 18V Fault codes & diagnostics

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

RegularSystem Natural GasLPG 18 kW 2007-2015 Discontinued
GC Number 41-288-11

Replaced by: Quinta Ace

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Severity at a glance

Each cell = one fault code. Hover to identify.
1 Emergency 48 High 3 Medium 3 Low
Just want the most common Remeha Avanta 18V faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 55 documented codes

Tap any card for details

b5

Your boiler has temporarily paused because it has reached the required temperature too quickly and is waiting for the system to cool down before restarting.

Low DIY-safe £0-120

What to check first

  1. Check that all radiator valves are fully open to allow heat to escape
  2. Ensure the central heating bypass valve is not closed
  3. Wait up to 10 minutes for the boiler to automatically restart

Parts commonly replaced

  • None (Normal operation)
  • Pump
  • Central heating filter (cleaning)

Related codes

Full explanation for b5
b8

Your boiler has temporarily paused because the water inside has become hotter than the temperature it was told to reach, often due to a circulation or sensor issue.

Medium DIY-safe £90-180

What to check first

  1. Check that all radiator valves are fully open to allow water to flow.
  2. Ensure the central heating system pressure is between 1.0 and 1.5 bar.
  3. Restart the boiler using the reset button to see if the fault clears.

Parts commonly replaced

  • Flow temperature sensor (NTC)
  • Circulation pump
  • Heat exchanger (descaling)

Related codes

Full explanation for b8
b9

Your boiler has shut down because it is heating up much faster than it can circulate water, indicating a blockage or a pump issue.

High DIY-safe £150-350

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 from the system

Parts commonly replaced

  • Circulation Pump
  • Flow/Return Temperature Sensors
  • Main Heat Exchanger (Cleaning)

Related codes

Full explanation for b9
code9

Your boiler has switched itself off because an external safety device, such as a thermostat or pressure switch, has detected an issue and broken the electrical circuit.

High DIY-safe £80-200

What to check first

  1. Check if your room thermostat or programmer is set too low or has run out of batteries
  2. If you have underfloor heating, check if the floor has overheated and tripped the safety limit
  3. Reset the boiler by pressing the reset button for two seconds

Parts commonly replaced

  • External Limit Thermostat
  • Gas Pressure Switch
  • Wiring harness or connector

Related codes

Full explanation for code9
E0

Your boiler has lost the ability to read the water temperature, so it has shut down as a precaution to prevent overheating.

High Engineer only £120-220

Parts commonly replaced

  • Flow temperature sensor (NTC)
  • Wiring harness

Related codes

Full explanation for E0
é0

Your boiler has detected a problem with its internal temperature sensors, meaning it cannot accurately tell how hot the water is and has shut down as a safety precaution.

High DIY-safe £100-190

What to check first

  1. Locate the reset button on the boiler control panel
  2. Press and hold the reset button for 2-3 seconds
  3. Wait to see if the error clears and the boiler restarts

Parts commonly replaced

  • Flow temperature sensor (NTC thermistor)
  • Return temperature sensor
  • Wiring harness

Related codes

Full explanation for é0
E01

Your boiler has tried to start up but cannot light the gas to create a flame.

High DIY-safe £100-280

What to check first

  1. Check that your gas supply is turned on at the meter.
  2. If you have a prepaid gas meter, check that you have remaining credit.
  3. Press the Reset button for two seconds to see if the boiler restarts.

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Spark generator

Related codes

Full explanation for E01
E1

Your boiler has failed to ignite properly and is currently trying to clear its internal system before attempting to start again.

High DIY-safe £120-350

What to check first

  1. Check that your gas emergency control valve is in the open position
  2. Ensure other gas appliances in your home are working to confirm gas supply
  3. Press and hold the 'Reset' button for two seconds once the 3-minute venting cycle has finished

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Flame sensing cable

Related codes

Full explanation for E1
é1

Your boiler has shut down because the water inside it has become too hot.

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 external pump (if visible) is running and not making a grinding noise.
  3. Press the Reset button once the boiler has had 15 minutes to cool down.

Parts commonly replaced

  • External Circulation Pump
  • Flow Temperature Sensor (NTC)
  • Main Heat Exchanger (Flushing)

Related codes

Full explanation for é1
E02

Your boiler has shut down because it has detected an internal temperature that is too high, often caused by a blockage or a pump failure.

High DIY-safe £120-£350

What to check first

  1. Check that your radiator valves are open and not turned to zero.
  2. Verify that the boiler pressure is between 1 and 2 bar.
  3. Press the 'Reset' button on the control panel to see if the fault clears.

Parts commonly replaced

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

Related codes

Full explanation for E02
Showing 11–20 of 55
E2

Your boiler is struggling to ignite or keep the flame burning, and it is now trying to clear itself out before attempting to start again.

High DIY-safe £100-350

What to check first

  1. Check if other gas appliances, like a hob, are working to ensure there is a gas supply.
  2. If you have a prepaid meter, check that you have enough credit.
  3. Press the Reset button once to see if the boiler restarts.

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Flame sensing cable

Related codes

Full explanation for E2
é2

Your boiler has detected that water is returning to the unit hotter than when it left, which usually indicates the internal sensors are confused or there is a problem with the way water is circulating.

High Engineer only £120-280

Parts commonly replaced

  • Flow temperature sensor
  • Return temperature sensor
  • Circulation pump
  • Main PCB

Related codes

Full explanation for é2
e3

Your boiler has detected an electrical safety issue where the power supply is not properly grounded or the internal control board has failed.

High Engineer only £100-£350

Parts commonly replaced

  • Control Unit (PCB)
  • Wiring Harness
  • Earth Connection/Ionisation Probe

Related codes

Full explanation for e3
E03

Your boiler has shut down because it detected that the exhaust gases are getting too hot, which is a safety measure to protect the internal components.

High Engineer only £120-£350

Parts commonly replaced

  • Heat exchanger (cleaning or replacement)
  • Flue gas thermostat/sensor
  • Flue seals

Related codes

Full explanation for E03
é3

Your boiler has detected an internal electrical problem or a grounding issue that is preventing it from running safely.

High Engineer only £180-£450

Parts commonly replaced

  • Control Unit (PCB)
  • Wiring Harness
  • Ignition Electrode

Related codes

Full explanation for é3
e4

Your boiler has tried to light several times but cannot establish a flame, meaning your heating and hot water will not work.

High DIY-safe £120-350

What to check first

  1. Check that your gas emergency control valve is open and you have credit on your gas meter.
  2. Check if other gas appliances in your home, such as a hob, are working correctly.
  3. Press the 'Reset' button on the boiler control panel for two seconds to see if it restarts.

Parts commonly replaced

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

Related codes

Full explanation for e4
E04

Your boiler's internal computer has encountered a critical error and has locked itself out for safety.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB (Control Board)
  • Wiring Loom

Related codes

Full explanation for E04
é4

Your boiler has tried to light itself several times but has failed, likely because there is no gas supply or the ignition part is dirty or broken.

High DIY-safe £100-280

What to check first

  1. Check if other gas appliances in your home, like a hob, are working to ensure gas is reaching the property.
  2. If you have a prepayment meter, check that you have remaining credit and the valve is open.
  3. Press the Reset button on the boiler control panel for one to two seconds.

Parts commonly replaced

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

Related codes

Full explanation for é4
e5

Your boiler has tried to light several times but cannot confirm that a flame has been successfully established.

High DIY-safe £120-350

What to check first

  1. Check that your gas emergency control valve is open and other gas appliances are working.
  2. Ensure your condensate pipe (the white plastic pipe outside) hasn't frozen in cold weather.
  3. Press the 'Reset' button on the boiler control panel for two seconds.

Parts commonly replaced

  • Ionisation probe
  • Ignition electrode
  • Gas valve
  • Ignition transformer

Related codes

Full explanation for e5
E05

Your boiler has stopped working because the internal fan, which safely exhausts gases, is not spinning at the correct speed.

High Engineer only £250-£450

Parts commonly replaced

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

Related codes

Full explanation for E05
Showing 21–30 of 55
é5

Your boiler is failing to detect a flame after several attempts, which means it has locked itself out for safety.

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. Press the 'Reset' button on the control panel to see if the boiler restarts
  3. In freezing weather, check if the white plastic condensate pipe outside is frozen and thaw it with warm water

Parts commonly replaced

  • Ionisation probe
  • Ignition electrode
  • Gas valve

Related codes

Full explanation for é5
e6

Your boiler detects a flame when it isn't supposed to be running, which is a safety conflict that prevents it from starting up.

High Engineer only £120-£350

Parts commonly replaced

  • Ionisation electrode
  • Ignition cable
  • Gas valve
  • PCB

Related codes

Full explanation for e6
E06

Your boiler is sensing a flame inside the unit even though it hasn't been told to ignite yet, which is causing it to shut down for safety.

High Engineer only £120-300

Parts commonly replaced

  • Ionisation electrode
  • Gas valve
  • Control PCB

Related codes

Full explanation for E06
é6

Your boiler has detected a flame when there shouldn't be one, which means it is locking out for safety reasons.

Emergency Engineer only £120-£350

Parts commonly replaced

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

Related codes

Full explanation for é6
E07

Your boiler is shutting down because the water is not circulating properly through the system, causing the heat to build up too quickly in one area.

High DIY-safe £120-280

What to check first

  1. Check that all radiator valves are fully open
  2. Ensure there is enough water pressure in the system (typically 1.0 to 1.5 bar)
  3. Bleed all radiators to remove trapped air that might be blocking circulation

Parts commonly replaced

  • Circulation Pump
  • Return thermistor
  • Main Heat Exchanger (cleaning)

Related codes

Full explanation for E07
E7

Your boiler is struggling to ignite or keep a flame going, causing it to shut down for a short safety cooling-down period.

High DIY-safe £120-350

What to check first

  1. Check that your gas stopcock is fully open.
  2. Verify if other gas appliances in your home, like a hob, are working.
  3. Try resetting the boiler by pressing the 'Reset' button for two seconds.

Parts commonly replaced

  • Ignition electrode
  • Ionisation probe
  • Gas valve

Related codes

Full explanation for E7
é7

Your boiler has detected that there is not enough water circulating through the system or the pump has stopped moving the water around.

High DIY-safe £180-350

What to check first

  1. Check the pressure gauge on your system and top it up to 1.5 bar if it is too low
  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
  4. Reset the boiler by pressing the 'Reset' button for two seconds

Parts commonly replaced

  • Circulation pump
  • Pressure sensor
  • Automatic air vent

Related codes

Full explanation for é7
e8

Your boiler has detected a problem with the fan that helps remove exhaust gases, which has caused the system to shut down for safety.

High Engineer only £280-450

Parts commonly replaced

  • Fan assembly
  • Circuit board (PCB)
  • Wiring harness

Related codes

Full explanation for e8
E08

Your boiler is shutting down because it cannot move the water around the system fast enough to keep it from overheating.

High Engineer only £150-300

Parts commonly replaced

  • Central heating pump
  • Flow sensor
  • Plate heat exchanger

Related codes

Full explanation for E08
E09

Your boiler is overheating because water isn't moving through the system fast enough to transfer heat away from the burner.

High Engineer only £150-300

Parts commonly replaced

  • Central heating pump
  • Plate heat exchanger
  • System filter

Related codes

Full explanation for E09
Showing 31–40 of 55
E9

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

High Engineer only £120-250

Parts commonly replaced

  • Central heating pump
  • Plate heat exchanger
  • Diverter valve
  • Safety thermostat

Related codes

Full explanation for E9
E10

Your boiler has detected that the water pressure is too low for the system to run safely and has shut down as a precaution.

High DIY-safe £80-220

What to check first

  1. Locate the external filling loop (usually a silver flexible hose) under or near the boiler.
  2. Slowly open the small valves at each end of the hose until you hear water flowing.
  3. Watch the pressure gauge and close the valves once the needle reaches between 1.0 and 1.5 bar.

Parts commonly replaced

  • Pressure sensor
  • Expansion vessel
  • Filling loop valve

Related codes

Full explanation for E10
E11

Your boiler has detected that water is returning much colder than it left, usually because it isn't moving through your radiators properly.

High DIY-safe £120-350

What to check first

  1. Check that all radiator valves (TRVs) are fully open
  2. Ensure your central heating pump is running and hasn't seized
  3. Bleed all radiators to remove trapped air that might be blocking water flow

Parts commonly replaced

  • Circulating Pump
  • NTC Temperature Sensors
  • Water Pressure Sensor

Related codes

Full explanation for E11
E12

Your boiler has sensed that the water inside is Getting too hot and has shut itself down as a safety precaution.

High DIY-safe £100-£350

What to check first

  1. Check that all radiator valves are fully open to allow water to circulate
  2. Ensure your system pressure is between 1.0 and 1.5 bar on the gauge
  3. Press the 'Reset' button for two seconds and release

Parts commonly replaced

  • Circulation pump
  • Flow temperature sensor (NTC)
  • Main heat exchanger (flushing or replacement)

Related codes

Full explanation for E12
E13

Your boiler has detected that the water coming back from your radiators is too hot, which usually means the water isn't flowing through your heating system properly.

High DIY-safe £120-350

What to check first

  1. Ensure all radiator valves (TRVs) are turned to their highest setting.
  2. Check that at least one radiator (usually the one in the hall) is fully open and not turned off.
  3. Check that the internal bypass valve or any external valves are in the open position.

Parts commonly replaced

  • Circulation Pump
  • Return Water Temperature NTC Sensor
  • External Bypass Valve

Related codes

Full explanation for E13
E14

Your boiler has detected a problem with the internal temperature sensor that monitors the water leaving the unit, causing the system to shut down for safety.

High Engineer only £90-180

Parts commonly replaced

  • NTC Flow Sensor
  • Wiring Harness
  • Main Control Board

Related codes

Full explanation for E14
E15

Your boiler has stopped working because a sensor that monitors the temperature of the water returning to the unit has developed a fault.

High Engineer only £90-160

Parts commonly replaced

  • Return NTC thermistor sensor
  • Wiring harness connector

Related codes

Full explanation for E15
E16

Your boiler has detected an issue with the sensor that monitors exhaust gases, and it has shut down for safety purposes.

High Engineer only £140-£260

Parts commonly replaced

  • Flue Gas NTC Sensor
  • Wiring Harness
  • Main Heat Exchanger cleaning

Related codes

Full explanation for E16
E31

Your boiler has lost the ability to monitor the temperature of your hot water, which means it will stop providing hot water until the faulty sensor is replaced.

High Engineer only £120-220

Parts commonly replaced

  • DHW temperature sensor (S6)

Related codes

Full explanation for E31
E32

Your boiler has detected an electrical fault with its temperature sensor, which means it cannot accurately monitor the water temperature and has shut down for safety.

High Engineer only £100-£180

Parts commonly replaced

  • NTC Flow Sensor
  • Wiring Harness

Related codes

Full explanation for E32
Showing 41–50 of 55
E34

Your boiler is struggling to push air through the system correctly, so it has safely shut itself down to prevent an unsafe combustion issue.

High Engineer only £180-350

Parts commonly replaced

  • Fan/Blower unit
  • Wiring harness
  • PCB (Printed Circuit Board)

Related codes

Full explanation for E34
E36

Your boiler started to heat up but the flame unexpectedly went out, causing the system to shut down for safety.

High DIY-safe £120-350

What to check first

  1. Check if other gas appliances (like a hob) are working to ensure gas is reaching the property
  2. Check if your gas meter has credit (if using a pre-payment meter)
  3. Reset the boiler by pressing the 'Reset' button for two seconds

Parts commonly replaced

  • Ionisation probe (Flame sensor)
  • Ignition electrode
  • Gas Valve

Related codes

Full explanation for E36
E37

Your boiler's internal computer has lost its connection with the main control panel, meaning the system can't send or receive the signals needed to heat your home.

High Engineer only £120-450

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
  • Wiring harness
  • Display interface

Related codes

Full explanation for E37
E38

Your boiler has stopped working because its internal temperature sensor that monitors water returning to the unit has developed an electrical fault.

High Engineer only £100-180

Parts commonly replaced

  • Return NTC thermistor sensor
  • Sensor wiring harness

Related codes

Full explanation for E38
E39

Your boiler has shut down because a remote safety device or clever external control has sent a signal to stop the system from running.

High Engineer only £120-250

Parts commonly replaced

  • External frost thermostat
  • Zone valve
  • Wiring link

Related codes

Full explanation for E39
E40

Your boiler has detected a problem with the sensor that monitors water pressure, meaning it cannot confirm if there is enough water to run safely.

High Engineer only £120-210

Parts commonly replaced

  • Water pressure sensor
  • Wiring harness

Related codes

Full explanation for E40
E41

Your boiler is struggling to accurately measure the temperature of the water being heated for your taps and showers.

Medium Engineer only £120-200

Parts commonly replaced

  • DHW temperature sensor (NTC)
  • Wiring harness

Related codes

Full explanation for E41
E42

Your boiler is struggling to move water around your heating system effectively, which is causing it to shut down to prevent overheating.

High DIY-safe £120-250

What to check first

  1. Check your boiler display for the water pressure reading; if it is below 1.0 bar, use your filling loop to top it up to roughly 1.5 bar.
  2. Ensure all your radiator valves are fully open to allow water to circulate freely.
  3. Restart the boiler once the pressure is correct to see if the fault clears.

Parts commonly replaced

  • Circulation pump
  • Heat exchanger
  • Flow sensor

Related codes

Full explanation for E42
e43

Your boiler's internal computer settings have become scrambled or have fallen outside of their safe operating ranges, causing the system to shut down for safety.

High Engineer only £100-350

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
  • Display PCB

Related codes

Full explanation for e43
e44

Your boiler has encountered a internal software error where it has failed to verify its own settings and operation parameters.

High DIY-safe £100-£350

What to check first

  1. Press the 'Reset' button on the front control panel for 3 seconds
  2. Switch off the electrical supply to the boiler for 60 seconds
  3. Turn the power back on and wait for the boiler to re-initialise

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Parameter Plug

Related codes

Full explanation for e44
Showing 51–55 of 55
e45

Your boiler has lost its configured settings and needs to be manually reprogrammed by a professional to function correctly again.

High Engineer only £120-250

Parts commonly replaced

  • Control Board (PCB)

Related codes

Full explanation for e45
Er18

Your boiler has detected an unusual temperature reading or a data processing error and has shut down as a safety precaution.

High Engineer only £120-350

Parts commonly replaced

  • Flow and Return Sensors (NTC)
  • Main Control PCB
  • Wiring harness

Related codes

Full explanation for Er18
f[ xx

Your boiler is simply performing a routine system check or displaying its internal software version, which is a normal operation and not a fault.

Low DIY-safe

What to check first

  1. Wait a few minutes for the cycle to finish
  2. Monitor the display to see if it returns to showing the current water temperature
  3. No action is required as this is not a fault
Full explanation for f[ xx
OT ERROR

Your boiler is staying on constantly because a safety sensor thinks the pipes are freezing, causing it to ignore your thermostat controls.

Medium Engineer only £120-220

Parts commonly replaced

  • External Frost Thermostat
  • Control PCB
  • Wiring harness

Related codes

Full explanation for OT ERROR