ECA Proteus Premix 24 HCH Fault codes & diagnostics

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

Regular Natural GasLPG 24 kW 2017-present
GC Number 41-814-01
Download the ECA Proteus Premix 24 HCH manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

The fault code is already on your display

Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →

Severity at a glance

Each cell = one fault code. Hover to identify.
1 Emergency 20 High 4 Medium 3 Low
Versions & GC numbers

Which version do you have?

The GC number on your boiler's data badge identifies the exact appliance and production years, as recorded in the UK Product Characteristics Database.

GC number Appliance (register name) Produced
41-814-01 PROTEUS PREMIX 24 HCH NG ERP UK 2017–present
Just want the most common ECA Proteus Premix 24 HCH faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 28 documented codes

Tap any card for details

E01

Your boiler has failed to ignite, meaning it cannot light the gas flame required to provide heating and hot water.

High DIY-safe £90-180

What to check first

  1. Check if other gas appliances, like a cooker, are working to ensure gas is reaching the property.
  2. Ensure your gas pre-payment meter is in credit.
  3. Press and hold the 'R' or reset button for 3 seconds to attempt a restart.

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Flame sensing cable

Related codes

Full explanation for E01
E02

Your boiler thinks a flame is burning even when it should be off, causing it to shut down for safety.

High Engineer only £120-250

Parts commonly replaced

  • Ionisation electrode
  • Ignition lead
  • Main PCB

Related codes

Full explanation for E02
E03

Your boiler has switched itself off because internal sensors have detected that the water inside the unit is getting too hot, preventing potential damage.

High DIY-safe £120-350

What to check first

  1. Check that your radiator valves are fully open to allow water to circulate.
  2. Ensure your system water pressure is between 1.0 and 1.5 bar on the gauge.
  3. Restart the boiler using the reset button once the unit has cooled down.

Parts commonly replaced

  • Circulation Pump
  • Overheat Thermostat
  • Main Heat Exchanger (de-scaling)

Related codes

Full explanation for E03
E05

Your boiler has stopped working because the internal fan, which safely clears exhaust fumes, is not spinning correctly or the boiler cannot detect its speed.

High Engineer only £220-£400

Parts commonly replaced

  • Extractor Fan
  • Main PCB
  • Wiring Harness

Related codes

Full explanation for E05
E08

Your boiler is failing to detect a flame or the flame is cutting out, so the system has shut down for safety.

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. Check that your gas prepayment meter has credit if applicable
  3. Perform a 'Reset' by turning the control knob to the R position for a few seconds

Parts commonly replaced

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

Related codes

Full explanation for E08
E09

Your boiler has detected a communication issue with its gas control unit, meaning it cannot safely regulate the fuel supply and has shut down as a precaution.

High Engineer only £180-350

Parts commonly replaced

  • Gas valve
  • Main PCB (Printed Circuit Board)
  • Wiring harness

Related codes

Full explanation for E09
E12

Your boiler's computer memory has suffered an internal error, meaning the main control board can no longer process the instructions needed to run the system.

High Engineer only £220-380

Parts commonly replaced

  • Main Printed Circuit Board (PCB)

Related codes

Full explanation for E12
E15

Your boiler has detected that the temperature sensors aren't reacting as quickly as expected, which usually means water isn't flowing correctly through the system.

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 1.0 and 1.5 bar on the pressure gauge
  3. Gently bleed air from your radiators using a radiator key

Parts commonly replaced

  • Temperature sensors (NTC thermistors)
  • Circulation pump
  • Main heat exchanger

Related codes

Full explanation for E15
E16

Your boiler has stopped working because it cannot correctly measure the temperature of the water being sent to your radiators.

High Engineer only £90-160

Parts commonly replaced

  • Central Heating (CH) Flow NTC Sensor
  • Sensor Wiring Harness

Related codes

Full explanation for E16
E17

Your boiler has stopped working because it cannot correctly measure the temperature of the water returning from your radiators.

High Engineer only £90-160

Parts commonly replaced

  • Central Heating Return NTC Sensor
  • Wiring harness / sensor connections

Related codes

Full explanation for E17
Showing 11–20 of 28
E18

Your boiler's temperature sensor for hot water has stopped working properly, meaning you may experience cold water or inconsistent temperatures.

Medium Engineer only £90-160

Parts commonly replaced

  • DHW Temperature Sensor (NTC Thermistor)
  • Wiring harness

Related codes

Full explanation for E18
E21

Your boiler's main control computer is failing to process internal signals correctly, causing it to shut down for safety.

High Engineer only £250-400

Parts commonly replaced

  • Main PCB
  • Wiring harness

Related codes

Full explanation for E21
E33

Your boiler is having trouble communicating with the sensor that monitors the temperature outside, which may cause your heating to run at the wrong temperature.

Low DIY-safe £90-160

What to check first

  1. Locate the external temperature sensor on your outside wall if you have one.
  2. Inspect the sensor and the visible wiring for any obvious signs of damage or loose connections.
  3. Press the Reset button on the boiler control panel to see if the fault clears.

Parts commonly replaced

  • Outdoor temperature sensor
  • External wiring cable

Related codes

Full explanation for E33
E35

Your boiler has lost its ability to accurately measure the temperature of the water used for your heating, causing the system to stop working for safety.

High Engineer only £90-160

Parts commonly replaced

  • Central Heating (CH) Flow NTC thermistor
  • Wiring harness

Related codes

Full explanation for E35
E80

Your boiler has detected that the water isn't circulating properly between the heating system and the unit, causing a temperature mismatch.

High Engineer only £120-250

Parts commonly replaced

  • Central Heating Pump
  • NTC Temperature Sensors
  • Diverter Valve

Related codes

Full explanation for E80
E82

Your boiler has failed to light several times and has locked itself out for safety.

High Engineer only £100-280

Parts commonly replaced

  • Ionization Electrode
  • Gas Valve
  • Ignition Lead
  • PCB

Related codes

Full explanation for E82
F07

Your boiler has switched itself off because the exhaust gases are getting too hot, which is a safety measure to prevent damage to the flue system.

High Engineer only £120-350

Parts commonly replaced

  • Flue gas NTC sensor
  • Main Heat Exchanger (descaling or replacement)
  • Burner gasket

Related codes

Full explanation for F07
F13

Your boiler has locked itself out because the reset button was pressed too many times in a short period while trying to clear another fault.

Medium DIY-safe £0-120

What to check first

  1. Turn the boiler power off at the main fused spur switch
  2. Wait for at least 30 to 60 minutes for the internal timer to clear
  3. Turn the power back on and see if the F13 code has disappeared
  4. Identify and resolve the original fault code that caused you to press reset initially

Parts commonly replaced

  • No parts usually required for F13
  • PCB (only if timer fail to reset)

Related codes

Full explanation for F13
F34

Your boiler has detected that the electricity supply coming into your home is too low for it to operate safely.

High Engineer only £100-350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • External Voltage Stabiliser

Related codes

Full explanation for F34
F37

Your boiler has detected that there is not enough water in the system to operate safely and has shut down.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (a flexible silver hose) underneath or near the boiler.
  2. Slowly open the valve(s) to let water into the system while watching the pressure gauge.
  3. Close the valves tightly once the pressure reaches between 1.0 and 1.5 bar.

Parts commonly replaced

  • Filling loop
  • Expansion vessel
  • Pressure sensor

Related codes

Full explanation for F37
Showing 21–28 of 28
F39

Your boiler is having trouble communicating with the sensor that measures the temperature outside, which may cause your heating to be less efficient or behave unexpectedly.

Low Engineer only £90-160

Parts commonly replaced

  • Outdoor Temperature Sensor
  • Sensor Wiring

Related codes

Full explanation for F39
F40

Your boiler has detected that there is too much water in the system, which puts extra stress on the internal components.

Emergency DIY-safe £60-180

What to check first

  1. Locate a radiator bleed valve and use a key to release water into a container until the pressure gauge on the boiler drops to 1.5 bar.
  2. Ensure the blue or black filling loop handles under the boiler are fully turned off.
  3. If the pressure continues to rise on its own, turn off the mains water stopcock and call a professional.

Parts commonly replaced

  • Expansion vessel
  • Filling loop valve
  • Pressure sensor

Related codes

Full explanation for F40
F47

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

High Engineer only £90-180

Parts commonly replaced

  • Water pressure sensor
  • Wiring harness
  • Main PCB

Related codes

Full explanation for F47
F50

Your boiler is struggling to monitor the temperature of your hot water tank, which usually means a internal sensor has stopped communicating correctly.

Medium Engineer only £90-160

Parts commonly replaced

  • NTC Storage Tank Sensor
  • Wiring harness / Connector

Related codes

Full explanation for F50
F51

Your boiler has detected a problem with the sensor monitoring your solar heating system, meaning these two systems are not communicating correctly.

Low Engineer only £90-180

Parts commonly replaced

  • PT1000 Solar Sensor
  • Sensor Wiring Harness

Related codes

Full explanation for F51
F52

Your boiler is having trouble measuring the temperature of your hot water, which usually means it cannot heat water for your taps and showers.

Medium Engineer only £90-160

Parts commonly replaced

  • DHW Temperature Sensor (NTC Thermistor)
  • Connecting wiring harness

Related codes

Full explanation for F52
F53

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

High Engineer only £90-180

Parts commonly replaced

  • Flue gas temperature sensor (NTC)
  • Wiring harness connectors

Related codes

Full explanation for F53
F81

Your boiler has detected that its temperature sensors are giving inconsistent readings, preventing it from heating up safely.

High Engineer only £90-180

Parts commonly replaced

  • NTC Temperature Sensor
  • Flow/Return Thermistor
  • Wiring Harness

Related codes

Full explanation for F81
Status & diagnostic codes

2 operating states & engineer diagnostics

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

AP Status Your boiler is simply running a routine cycle to clear air bubbles out of the system and is not actually at fault. ASE Diagnostic Your boiler is simply displaying a helpful reminder that its annual service is due soon to ensure it continues running safely and efficiently.
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