Remeha Avanta Plus 28c Fault codes & diagnostics

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

Combi Natural Gas 24 kW 2006-2016 Discontinued

Replaced by: Remeha Avanta Ace

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Severity at a glance

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31 High 2 Medium 2 Low
Just want the most common Remeha Avanta Plus 28c faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 35 documented codes

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b5

Your boiler has temporarily paused because it has reached its target temperature while your heating is still turned on, often caused by poor water circulation through the radiators.

Low DIY-safe £0-120

What to check first

  1. Ensure all radiator valves (TRVs) are fully open to allow water to flow.
  2. Check that the boiler pressure is between 1.0 and 1.5 bar.
  3. Bleed your radiators to remove any trapped air pockets.

Parts commonly replaced

  • None (Adjustment only)
  • Circulation pump
  • Bypass valve

Related codes

Full explanation for b5
b8

Your boiler has temporarily stopped because the water inside has reached its maximum target temperature and it is waiting for the system to cool down before firing up again.

Low DIY-safe £0-120

What to check first

  1. Ensure at least one or two radiators have their valves turned fully open to allow heat to circulate.
  2. Check that the pump is running and not stuck.
  3. Wait for the boiler to cool down naturally; it should restart automatically once the temperature drops.

Parts commonly replaced

  • None (operational state)
  • Circulation Pump
  • Flow Temperature Sensor (NTC)

Related codes

Full explanation for b8
b9

Your boiler has shut down because water isn't moving through the system quickly enough, causing it to overheat too fast.

High DIY-safe £120-350

What to check first

  1. Check that the boiler pressure is between 1.0 and 1.5 bar on the pressure gauge.
  2. Ensure all radiator valves are fully open and not turned off.
  3. Wait 10 minutes for the boiler to automatically attempt a restart.

Parts commonly replaced

  • Circulating pump
  • Main heat exchanger (flushing)
  • Flow/Return temperature sensors

Related codes

Full explanation for b9
E0

Your boiler has detected that a temperature sensor has lost its connection or failed, which means it cannot tell how hot the water is and has stopped running for safety.

High Engineer only £90-160

Parts commonly replaced

  • Flow temperature sensor (NTC thermistor)
  • Sensor wiring harness

Related codes

Full explanation for E0
é0

Your boiler has detected a problem with its internal temperature sensors, which means it cannot monitor heat levels safely and has stopped working.

High Engineer only £120-£200

Parts commonly replaced

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

Related codes

Full explanation for é0
E1

Your boiler has detected a fault with the internal thermometer that monitors water temperature, causing the system to shut down for safety.

High Engineer only £90-160

Parts commonly replaced

  • Flow temperature sensor (NTC)
  • Wiring harness

Related codes

Full explanation for E1
é1

Your boiler has reached an unsafely high internal temperature, likely because there is not enough water flowing through the system to carry the heat away.

High DIY-safe £100-280

What to check first

  1. Check the boiler pressure gauge and top it up to 1.5 bar using the filling loop if it is too low.
  2. Ensure all radiator valves are fully open and not turned off.
  3. Bleed all radiators to remove trapped air which may be blocking water flow.
  4. Reset the boiler by pressing the reset button for two seconds.

Parts commonly replaced

  • Circulation Pump
  • Flow/Return Temperature Sensor (NTC)
  • Main Heat Exchanger (Cleaning/Descaling)

Related codes

Full explanation for é1
E2

Your boiler has detected that a sensor monitoring the water coming back into the unit has disconnected or stopped working, causing the system to shut down for safety.

High Engineer only £90-160

Parts commonly replaced

  • Return temperature sensor (NTC thermistor)
  • Sensor wiring harness

Related codes

Full explanation for E2
é2

Your boiler has stopped working because water is not moving through the system properly or there is too much air trapped inside.

High DIY-safe £100-250

What to check first

  1. Check that your system pressure is between 1.0 and 1.5 bar on the pressure gauge.
  2. Bleed all radiators to remove trapped air that might be blocking water flow.
  3. Ensure all radiator valves and any isolation valves under the boiler are fully open.

Parts commonly replaced

  • Flow/Return temperature sensors (NTC)
  • Circulation pump
  • Automatic air vent

Related codes

Full explanation for é2
E3

Your boiler has detected a fault with the sensor that monitors water returning to the unit, meaning it cannot safely regulate temperature and has shut down as a precaution.

High Engineer only £90-160

Parts commonly replaced

  • Return temperature sensor (NTC thermistor)
  • Sensor wiring harness

Related codes

Full explanation for E3
Showing 11–20 of 35
E4

Your boiler has detected a fault with an internal sensor that monitors the temperature inside the heat exchanger, meaning it cannot safely heat your water.

High Engineer only £100-£190

Parts commonly replaced

  • Heat exchanger temperature sensor (S3)
  • Sensor wiring harness

Related codes

Full explanation for E4
E5

Your boiler has detected a technical fault with an internal temperature monitor and has shut down to prevent any damage.

High Engineer only £90-160

Parts commonly replaced

  • Heat exchanger temperature sensor (S3)
  • Sensor wiring harness

Related codes

Full explanation for E5
e6

Your boiler detects a flame when there shouldn't be one, meaning the internal safety controls have stopped the system to prevent an unsafe situation.

High Engineer only £250-£450

Parts commonly replaced

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

Related codes

Full explanation for e6
E7

Your boiler has effectively switched itself off because it has detected that it is getting too hot inside.

High DIY-safe £120-350

What to check first

  1. Check that all radiator valves (TRVs) are fully open to allow water to circulate
  2. Ensure the boiler pressure is between 1.0 and 1.5 bar on the gauge
  3. Press the Reset button for two seconds once the system has cooled down

Parts commonly replaced

  • Circulating Pump
  • Overheat Thermostat (High Limit Stat)
  • Flow/Return Temperature Sensors

Related codes

Full explanation for E7
e8

Your boiler has detected a problem with the internal fan that clears waste gases, preventing the system from starting up safely for use.

High Engineer only £250-450

Parts commonly replaced

  • Extraction Fan
  • Internal Fan Wiring Harness
  • Main Control Board (PCB)

Related codes

Full explanation for e8
E9

Your boiler has sensed it is getting too hot and has shut itself down as a safety precaution to prevent damage.

High DIY-safe £100-£350

What to check first

  1. Check that your radiator valves are open to allow water to flow
  2. Check that your boiler pressure is between 1 and 1.5 bar on the gauge
  3. Press the 'Reset' button for two seconds once the boiler has cooled down

Parts commonly replaced

  • Circulation pump
  • High limit thermostat
  • Main heat exchanger (flushing/cleaning)

Related codes

Full explanation for E9
E10

Your boiler has detected that the water pressure in the central heating system is too low for it to operate safely.

High DIY-safe £90-180

What to check first

  1. Locate the silver braided filling loop hoses underneath or near the boiler
  2. Slowly open both black lever valves to allow water into the system
  3. Close both valves once the pressure gauge on the boiler screen reads between 1.0 and 1.5 bar
  4. Press the 'Reset' button on the control panel to clear the code

Parts commonly replaced

  • Water pressure sensor
  • Filling loop valves
  • Expansion vessel recharge

Related codes

Full explanation for E10
E11

Your boiler's computer brain has encountered an internal software or hardware glitch and cannot safely tell the heating to turn on.

High Engineer only £250-£450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

Full explanation for E11
E12

Your boiler has switched itself off because it has detected that the internal water temperature has become dangerously hot.

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 and 2 bar
  3. Press the 'Reset' button on the control panel
  4. Check if the pump is making unusual noises or is stuck

Parts commonly replaced

  • Circulation pump
  • Overheat thermostat
  • Main heat exchanger (flushing requirement)

Related codes

Full explanation for E12
E13

Your boiler has detected that a safety sensor monitoring the temperature of the exhaust fumes has failed or developed a short circuit, causing the system to shut down for safety.

High Engineer only £120-£200

Parts commonly replaced

  • Flue gas temperature sensor (NTC)
  • Sensor wiring harness
  • Main PCB

Related codes

Full explanation for E13
Showing 21–30 of 35
E14

Your boiler has detected that the temperature sensors on the main pipes are either installed in the wrong positions or are reporting conflicting readings.

High Engineer only £90-180

Parts commonly replaced

  • Flow Temperature Sensor
  • Return Temperature Sensor
  • Sensor Wiring Loom

Related codes

Full explanation for E14
E15

Your boiler has detected that the exhaust gases are getting too hot, so it has shut down to protect itself from internal damage.

High Engineer only £150-450

Parts commonly replaced

  • Main Heat Exchanger
  • Flue Gas Temperature Sensor (S5)
  • Heat Exchanger Insulation Plate

Related codes

Full explanation for E15
E16

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

High Engineer only £120-£200

Parts commonly replaced

  • Flue gas temperature sensor (S5)
  • Wiring harness
  • Heat exchanger cleaning

Related codes

Full explanation for E16
E31

Your boiler has detected a fault with the sensor that monitors your hot water temperature, meaning it cannot safely heat water for your taps.

High Engineer only £90-160

Parts commonly replaced

  • DHW Temperature Sensor (NTC)
  • Connecting wiring harness

Related codes

Full explanation for E31
E32

Your boiler has lost connection with the sensor that monitors your hot water temperature, meaning it cannot safely heat water for your taps.

Medium Engineer only £90-160

Parts commonly replaced

  • DHW Temperature Sensor (NTC)
  • Sensor Wiring Harness

Related codes

Full explanation for E32
E36

Your boiler is struggling to keep a flame lit, causing it to shut down for safety after five unsuccessful attempts to restart.

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 for two seconds to see if the boiler restarts

Parts commonly replaced

  • Ionisation probe
  • Ignition electrode
  • Gas valve
  • PCB

Related codes

Full explanation for E36
E37

Your boiler's computer brains are having trouble talking to each other, which means the system has shut down for safety.

High Engineer only £180-£450

Parts commonly replaced

  • Safety Unit (SU) PCB
  • Main Control Board
  • Wiring Harness

Related codes

Full explanation for E37
E38

Your boiler's internal computer is having trouble communicating with its main safety control board, meaning the system has shut down for protection.

High Engineer only £180-350

Parts commonly replaced

  • SCU (Safety Control Unit)
  • Main PCB
  • Internal wiring harness

Related codes

Full explanation for E38
E39

Your boiler has shut down because an external safety device or sensor has detected a limit that requires the system to stop for protection.

High Engineer only £90-250

Parts commonly replaced

  • External limit thermostat
  • Frost thermostat
  • Wiring harness
  • Control PCB

Related codes

Full explanation for E39
E40

Your boiler's energy-saving heat recovery unit has failed an internal safety check, causing the system to stop working as a precaution.

High Engineer only £180-450

Parts commonly replaced

  • Heat Recovery Unit (HRU)
  • Main PCB
  • Wiring Harness

Related codes

Full explanation for E40
Showing 31–35 of 35
E41

Your boiler has detected a problem with the internal sensor that monitors the temperature of your hot water, which may cause your hot water to stop working or fluctuate in temperature.

Medium Engineer only £90-160

Parts commonly replaced

  • DHW Temperature Sensor (NTC)
  • Sensor Wiring Harness

Related codes

Full explanation for E41
E42

Your boiler is struggling to circulate water properly because there is either not enough water in the system or a blockage is preventing it from flowing through the pipes.

High DIY-safe £80-250

What to check first

  1. Check the pressure gauge on the front of the boiler; if it is below 1.0 bar, use the filling loop to top it up to 1.5 bar.
  2. Ensure all radiator valves and the boiler isolation valves are fully open.
  3. Bleed your radiators to remove any trapped air that might be blocking water flow.

Parts commonly replaced

  • Circulation Pump
  • Central Heating Filter
  • Flow and Return Temperature Sensors

Related codes

Full explanation for E42
E43

Your boiler's internal computer has encountered a memory error and cannot safely process its settings, causing the system to shut down for safety.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB (Control Board)
  • Safety Unit (SU)

Related codes

Full explanation for E43
e44

Your boiler’s internal computer has encountered a configuration error or memory issue, meaning it does not recognize its own operating settings.

High Engineer only £120-450

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
  • Parameters Plug

Related codes

Full explanation for e44
e45

Your boiler's internal computer has lost its saved settings and is no longer communicating correctly with its own components.

High Engineer only £120-350

Parts commonly replaced

  • Main PCB
  • Control Board Display Unit

Related codes

Full explanation for e45