Remeha Avanta 28c Fault codes & diagnostics

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

Combi Natural Gas 24 kW 2006-2016 Discontinued

Replaced by: Avanta Ace

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Severity at a glance

Each cell = one fault code. Hover to identify.
3 Emergency 43 High 3 Medium 4 Low

All 53 documented codes

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b5

Your boiler is simply taking a short, scheduled break because the water in your radiators has already reached the temperature set on the dial.

Low DIY-safe

What to check first

  1. Check if your thermostat or boiler temperature dial is set to a comfortable level
  2. Ensure your radiator valves are fully open to allow heat to circulate
  3. Wait 10 minutes to see if the boiler restarts automatically once the water temperature drops

Related codes

b8

Your boiler has temporarily paused heating because the water inside is already warmer than the temperature you have requested.

Low DIY-safe

What to check first

  1. Check if your room thermostat or boiler temperature dial is set lower than the current water temperature.
  2. Ensure your radiators are not all turned off, which can cause heat to build up inside the unit.
  3. Wait for the boiler to cool down; it will restart automatically once the internal temperature drops.

Parts commonly replaced

  • Flow sensor
  • NTC temperature sensor

Related codes

b9

Your boiler has shut down because it is overheating or detecting that water isn't flowing through the system properly, so it is taking a short break to prevent damage.

High Engineer only £120-250

Parts commonly replaced

  • Pump
  • Plate heat exchanger
  • Temperature sensors

Related codes

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

é0

Your boiler has lost the ability to accurately measure the water temperature, so it has shut down to prevent potential overheating.

High Engineer only £120-220

Parts commonly replaced

  • Flow temperature sensor
  • Return temperature sensor
  • Wiring harness

Related codes

E01

Your boiler is trying to start up, but it cannot successfully light the internal flame after several attempts, so it has shut down for safety.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Flame rectification probe

Related codes

E1

Your boiler has detected an issue with the water circulation and has safely shut down, requiring a specific reset procedure to clear the fault.

High Engineer only £120-250

Parts commonly replaced

  • Circulation pump
  • Flow sensor
  • Heat exchanger

Related codes

é1

Your boiler has switched itself off because it has detected that the water inside is getting too hot, likely due to low water pressure or trapped air in your radiators.

High DIY-safe £120-250

What to check first

  1. Check your boiler's pressure gauge and top it up to 1.5 bar if it is below 1 bar
  2. Bleed all radiators in your home to release any trapped air
  3. Ensure all radiator valves are fully open to allow water to flow freely

Parts commonly replaced

  • NTC Temperature Sensor
  • Central Heating Pump

Related codes

E02

Your boiler has automatically shut down because it has detected that its internal water temperature has become dangerously hot.

High Engineer only £120-250

Parts commonly replaced

  • Diverter valve
  • Central heating pump
  • Safety thermostat (STB)
  • NTC sensor

Related codes

E2

Your boiler has detected that it is not heating the water effectively, often caused by trapped air in the system or a temporary lockout that requires a reset.

High Engineer only £120-250

Parts commonly replaced

  • Air pressure switch
  • Circulation pump
  • NTC sensor

Related codes

Showing 11–20 of 53
é2

Your boiler has detected that hot water is flowing in the wrong direction or is blocked, which usually means the system lacks enough water or has trapped air preventing a proper flow.

High DIY-safe £120-250

What to check first

  1. Check your boiler pressure gauge; if it is below 1 bar, top up the system using the filling loop
  2. Bleed all radiators in the house starting from the ground floor up to the top floor to release trapped air
  3. Ensure all radiator thermostatic valves are fully open to allow water to circulate freely

Parts commonly replaced

  • NTC Temperature sensors
  • Central heating pump
  • Pressure relief valve

Related codes

E03

Your boiler has detected that the exhaust gases are getting too hot and has safely shut itself down to prevent damage or overheating.

Emergency Engineer only £120-250

Parts commonly replaced

  • Flue gas temperature sensor
  • Heat exchanger
  • Main PCB

Related codes

E3

Your boiler has detected an internal electrical fault with a temperature sensor, which has caused it to shut down for safety reasons.

High Engineer only £120-220

Parts commonly replaced

  • Return temperature sensor (S2)
  • Wiring harness

Related codes

é3

Your boiler has detected an internal electrical safety fault or a problem with its 'brain' and has shut down to prevent damage or operation in an unsafe state.

High Engineer only £180-350

Parts commonly replaced

  • Control unit (PCB)
  • Wiring harness
  • Ignition cable

Related codes

E04

Your boiler has failed to light after several attempts and has locked itself out for safety reasons.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Ionisation probe
  • Condensate trap

Related codes

E4

Your boiler has stopped working because it can no longer accurately measure the temperature inside its internal heating component.

High Engineer only £150-250

Parts commonly replaced

  • S3 Temperature sensor
  • Wiring harness

Related codes

é4

Your boiler has failed to light the flame after several attempts and has switched itself off to prevent a build-up of unburnt gas.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Ignition transformer

Related codes

E05

Your boiler's internal computer is experiencing a software or hardware failure and has shut down as a safety precaution to prevent incorrect operation.

High Engineer only £250-450

Parts commonly replaced

  • Main Control Board (PCB)
  • Wiring harness

Related codes

E5

Your boiler is failing to light the flame or keep it running, so it has safely locked itself off to prevent gas from escaping.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Flame rectification lead

Related codes

é5

Your boiler is failing to light the flame or keep it running, so it has stopped working to keep your home safe.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Ignition transformer

Related codes

Showing 21–30 of 53
E06

Your boiler has detected a failure within its own brain, meaning it has safely shut itself down to prevent unpredictable operation.

High Engineer only £250-450

Parts commonly replaced

  • Main Control PCB
  • Wiring harness

Related codes

E6

Your boiler is detecting a flame when it should be turned off, which indicates a serious internal safety fault.

Emergency Engineer only £250-450

Parts commonly replaced

  • Gas valve
  • Control unit (PCB)
  • Wiring harness

Related codes

é6

Your boiler has detected a flame firing when it shouldn't be, which is a safety concern that prevents the system from operating to protect your home.

Emergency Engineer only £150-300

Parts commonly replaced

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

Related codes

E07

Your boiler has detected that the water inside the system has become dangerously hot and has shut itself down to prevent damage or overheating.

High Engineer only £150-300

Parts commonly replaced

  • Pump
  • Plate heat exchanger
  • Sensor leads

Related codes

E7

Your boiler has detected air in the system or a circulation issue and has safely shut itself down to prevent damage.

Medium Engineer only £120-200

Parts commonly replaced

  • Automatic air vent
  • Pump
  • Pressure sensor

Related codes

é7

Your boiler has detected that the water pressure inside the system is far too low to function safely.

High DIY-safe £80-150

What to check first

  1. Locate the filling loop (usually two silver taps connected by a braided hose) underneath the boiler.
  2. Gradually open the taps to let mains water into the heating system until the pressure gauge reads between 1.0 and 1.5 bar.
  3. Close both taps tightly and check the display to see if the error has cleared.

Parts commonly replaced

  • Pressure relief valve
  • Filling loop
  • System pressure sensor

Related codes

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

E8

Your boiler has detected a problem with the internal fan unit, which is responsible for safely venting fumes outside, and as a safety precaution, it has stopped working to prevent unsafe operation.

High Engineer only £200-350

Parts commonly replaced

  • Fan assembly
  • Fan wiring harness
  • PCB

Related codes

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

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

Showing 31–40 of 53
E10

Your boiler has stopped working because the water pressure inside the heating system has dropped too low.

High DIY-safe £80-150

What to check first

  1. Locate the filling loop (a flexible metal hose) under the boiler.
  2. Open the valves until the pressure gauge on the front reads between 1.0 and 1.5 bar.
  3. Close the valves tightly and turn the boiler off and back on again to reset.

Parts commonly replaced

  • Water pressure sensor
  • Filling loop

Related codes

E11

Your boiler's computer is experiencing an internal error and cannot operate safely, so it has shut itself down to prevent further damage.

High Engineer only £250-450

Parts commonly replaced

  • Main Control Board (PCB)

Related codes

E12

Your boiler has automatically turned itself off because it has detected dangerously high temperatures inside the unit to prevent potential damage.

High Engineer only £150-300

Parts commonly replaced

  • Central heating pump
  • Heat exchanger
  • NTC sensor
  • Diverter valve

Related codes

E13

Your boiler has detected a faulty reading from its internal safety monitoring system, so it has safely shut down to prevent any potential overheating.

High Engineer only £150-250

Parts commonly replaced

  • Flue gas temperature sensor (S5)
  • Wiring harness

Related codes

E14

Your boiler is confused because its temperature measurement sensors have been installed in the wrong places or have become disconnected.

High Engineer only £120-200

Parts commonly replaced

  • NTC sensor
  • Wiring harness

Related codes

E15

Your boiler has detected that the exhaust gases leaving the unit are dangerously hot, so it has safely shut itself down to prevent damage.

High Engineer only £150-300

Parts commonly replaced

  • Flue gas sensor
  • Heat exchanger
  • Primary flow sensor

Related codes

E16

Your boiler has detected a faulty connection to the sensor that monitors the temperature of the exhaust fumes, causing it to shut down for safety reasons.

High Engineer only £120-220

Parts commonly replaced

  • Flue gas temperature sensor
  • Wiring harness

Related codes

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

E32

Your boiler's temperature monitoring system for the water returning to the unit has stopped working correctly, so the boiler has shut down to prevent potential overheating.

High Engineer only £120-180

Parts commonly replaced

  • Return temperature sensor (T2)
  • Wiring harness

Related codes

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

Showing 41–50 of 53
E36

Your boiler has failed to stay lit and has now locked itself out as a safety precaution, meaning you currently have no heating or hot water.

High Engineer only £150-350

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Flame rectification probe

Related codes

E37

Your boiler has lost the ability for its internal computer boards to talk to each other, preventing it from starting safely.

High Engineer only £150-300

Parts commonly replaced

  • Safety Unit (SU)
  • Wiring harness
  • Control board (PCU)

Related codes

E38

Your boiler has lost the ability for its internal computer to 'talk' to its safety sensors, so it has shut down to keep you safe.

High Engineer only £150-300

Parts commonly replaced

  • Safety Control Unit (SCU)
  • Wiring harness
  • Main circuit board (PCB)

Related codes

E39

Your boiler has detected an external safety signal, such as a cold protection device or an add-on safety switch, that is preventing it from firing up.

High Engineer only £120-250

Parts commonly replaced

  • External frost thermostat
  • External limit switch
  • Wiring loom

Related codes

E40

Your boiler has detected an internal fault within its heat recovery system, which means it has safely shut itself down to prevent potential damage.

High Engineer only £150-300

Parts commonly replaced

  • Main PCB
  • HRU sensor
  • Wiring harness

Related codes

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

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

E43

Your boiler’s internal computer chip has encountered a memory error and cannot safely manage the system, meaning it has shut down to protect itself.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB
  • Safety Unit (SU)

Related codes

E44

The boiler's internal computer has detected a contradiction in its settings, meaning it cannot safely start up and needs a professional to recalibrate the software.

High Engineer only £120-250

Parts commonly replaced

  • Control board
  • GSU (Gas Service Unit)

Related codes

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

Showing 51–53 of 53
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
OT ERROR

Your boiler's external temperature sensor and frost protection thermostat are sending conflicting signals to your heating controller.

Medium Engineer only £120-200

Parts commonly replaced

  • Outside temperature sensor
  • Frost thermostat
  • Wiring harness

Related codes