Ravenheat 100 Fault codes & diagnostics

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

Combi Natural Gas 29.3 kW 1994-2005 Discontinued

Replaced by: HE series

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Each cell = one fault code. Hover to identify.
45 High 4 Medium

All 49 documented codes

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01

Your boiler has failed to light and is not producing heat or hot water because it is not receiving fuel or cannot generate a spark.

High Engineer only £120-350

Parts commonly replaced

  • Gas Valve
  • Ignition PCB
  • Fan
  • Spark Electrode

Related codes

02

Your boiler has stopped working because it has detected an incorrect temperature reading and needs to be restarted.

High DIY-safe £100-220

What to check first

  1. Locate the reset button or dial on the front control panel
  2. Press and hold the reset button for five seconds
  3. Wait for the boiler to complete its start-up sequence

Parts commonly replaced

  • NTC Temperature Sensor
  • Overheat Thermostat
  • Main PCB

Related codes

02E

Your boiler has stopped working because the water isn't moving through the system properly.

High DIY-safe £180-350

What to check first

  1. Check that your radiator valves are open
  2. Ensure the system pressure is between 1.0 and 1.5 bar on the gauge
  3. Gently bleed your radiators to remove any trapped air

Parts commonly replaced

  • Circulation Pump
  • Flow Temperature Sensor
  • Main Heat Exchanger

Related codes

03E

Your boiler is struggling to accurately track how water is moving through the system, which prevents it from heating up correctly.

High Engineer only £120-£200

Parts commonly replaced

  • Flow sensor
  • NTC thermistor
  • Wiring harness

Related codes

04

Your boiler has switched itself off because it has reached a temperature that is too high, often caused by a circulation problem or a faulty safety sensor.

High DIY-safe £90-180

What to check first

  1. Identify if your radiator valves are closed and open them fully
  2. Check your boiler pressure gauge and top up to 1.5 bar if it is too low
  3. Press the 'Reset' button on the control panel to see if the fault clears

Parts commonly replaced

  • Overheat Thermostat (Limit Statutory)
  • Circulation Pump
  • Thermistor (NTC Sensor)

Related codes

04E

Your boiler is having trouble measuring the temperature of your hot water, which means your taps and showers may not get warm.

Medium Engineer only £90-160

Parts commonly replaced

  • DHW Thermistor (NTC Sensor)
  • Connecting wiring harness

Related codes

05E

Your boiler has detected an issue where the fan is not spinning correctly or communicating with the system, preventing the boiler from starting for safety reasons.

High Engineer only £180-350

Parts commonly replaced

  • Fan Assembly
  • Air Pressure Switch
  • PCB

Related codes

06E

Your boiler has detected that the temperature near the heating sensor has become too high, causing the system to shut down for safety.

High Engineer only £120-250

Parts commonly replaced

  • NTC Temperature Sensor
  • Circulation Pump
  • Main Heat Exchanger

Related codes

08E

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

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (usually a silver braided hose) under the boiler.
  2. Slowly open the valve(s) until you hear water flowing into the system.
  3. Watch the pressure gauge and close the valves once the needle reaches 1.5 bar.
  4. Press the reset button to restart the boiler.

Parts commonly replaced

  • Filling loop
  • Pressure sensor
  • Expansion vessel
09E

Your boiler has become too hot and has shut down as a safety precaution to prevent internal damage.

High Engineer only £120-280

Parts commonly replaced

  • Overheat Thermostat
  • Main Heat Exchanger
  • Circulating Pump

Related codes

Showing 11–20 of 49
10E

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

Medium DIY-safe £90-180

What to check first

  1. Check that the filling loop valves are fully closed
  2. Bleed water from a radiator using a bleed key to reduce pressure
  3. Monitor the pressure gauge until it returns to between 1.0 and 1.5 bar
  4. Reset the boiler once the pressure is correct

Parts commonly replaced

  • Filling loop valve
  • Expansion vessel
  • Pressure relief valve

Related codes

12

Your boiler's internal thermometer for the heating system has stopped working correctly, meaning the unit cannot accurately measure water temperature to run effectively.

High Engineer only £90-160

Parts commonly replaced

  • NTC Thermistor (Heating)
  • Wiring Harness
13E

Your boiler's computer brain has encountered a software glitch and is unable to run the system correctly.

High DIY-safe £280-450

What to check first

  1. Turn the boiler power switch to the 'OFF' position
  2. Wait for approximately 30 seconds
  3. Turn the power switch back to the 'ON' position to reset the internal software

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
17

Your boiler has stopped working because the fan is not receiving the correct amount of electrical power to safely exhaust fumes.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Wiring harness
21E

Your boiler has detected that the water flowing back from your radiators is too hot, causing the system to shut down for safety.

High DIY-safe £100-220

What to check first

  1. Check that all radiator valves are fully open
  2. Ensure there are no obstructions around the boiler's external vents
  3. Reset the boiler using the control knob once the system has cooled down

Parts commonly replaced

  • Central heating return thermistor (NTC sensor)
  • Circulation pump
  • Main heat exchanger (flushing)

Related codes

22E

Your boiler has shut down because it or the exhaust gases are getting too hot, which is a safety mechanism to prevent damage or dangerous fumes.

High Engineer only £120-280

Parts commonly replaced

  • Flue Thermistor
  • Heat Exchanger
  • Main PCB

Related codes

23E

Your boiler has detected a problem with the sensor that monitors the exhaust gases, and as a safety precaution, it has stopped running to prevent overheating.

High Engineer only £120-190

Parts commonly replaced

  • Flue Gas NTC Sensor
  • Sensor Wiring Harness

Related codes

24E

Your boiler has detected a problem with the sensor that monitors the water temperature returning from your radiators, meaning it cannot safely regulate the central heating.

High Engineer only £90-160

Parts commonly replaced

  • Central heating return NTC thermistor
  • Wiring harness connector

Related codes

25E

Your boiler's internal heating unit has become so cold that the water inside it has frozen, preventing the system from operating.

High DIY-safe £80-250

What to check first

  1. Increase the room thermostat setting to encourage the boiler to fire up.
  2. Check if the external condensate pipe is frozen and gently thaw it with warm (not boiling) water.
  3. Reset the boiler several times once the surrounding temperature has risen.

Parts commonly replaced

  • Main Heat Exchanger
  • Condensate Pipe Insulation
  • Temperature Sensor

Related codes

28

Your boiler has detected that there is not enough water pressure or flow to operate safely.

High DIY-safe £100-280

What to check first

  1. Check the pressure gauge on the front of the boiler; it should be between 1 and 1.5 bar.
  2. If the pressure is too low, use the filling loop to top up the water level.
  3. Reset the boiler once the correct pressure is reached.

Parts commonly replaced

  • Low water pressure switch
  • Circulation pump

Related codes

Showing 21–30 of 49
29E

Your boiler has detected that the water used for your taps and shower is getting too hot, causing the system to shut down for safety.

High Engineer only £90-180

Parts commonly replaced

  • Domestic Hot Water (DHW) thermistor
  • DHW temperature sensor
  • Wiring harness

Related codes

30

Your boiler has sensed that the exhaust gases are getting too hot and has shut itself down as a safety precaution.

High Engineer only £120-300

Parts commonly replaced

  • Flue Thermistor
  • Heat Exchanger
  • Main PCB

Related codes

31

Your boiler has detected that the exhaust gases are not at the correct temperature, causing the system to shut down as a safety precaution.

High Engineer only £90-180

Parts commonly replaced

  • Flue Temperature Sensor (NTC)
  • Main Heat Exchanger cleaning
  • Wiring Loom
31E

Your boiler is having trouble 'talking' to your smart thermostat or external controls, meaning it cannot receive the correct instructions to heat your home.

High DIY-safe £90-180

What to check first

  1. Check that your smart thermostat or wall controller is powered on and has fresh batteries if required
  2. Ensure any external receiver box plugged into the wall has power lights visible
  3. Restart your Wi-Fi router if your heating controls rely on an internet bridge

Parts commonly replaced

  • OpenTherm Interface Bridge
  • Thermostat Receiver
  • Control PCB
41E

Your boiler has detected that water is not circulating correctly through the system, causing an unusual temperature gap between the pipes.

High DIY-safe £120-£350

What to check first

  1. Check that all radiator valves are fully open
  2. Check the boiler pressure gauge and top up to 1.5 bar if it is low
  3. Bleed any air out of your radiators using a radiator key

Parts commonly replaced

  • Circulation pump
  • Flow and return thermistors
  • Main heat exchanger (de-scaling)

Related codes

42E

Your boiler has detected that the temperature sensors are giving conflicting readings, causing it to shut down for safety.

High DIY-safe £120-250

What to check first

  1. Turn the boiler off and wait 10 minutes for it to cool down
  2. Check that your radiator valves are open and not blocked
  3. Press the reset button once to see if the error clears

Parts commonly replaced

  • NTC Temperature Sensors
  • Central Heating Pump
  • Main PCB

Related codes

44E

Your boiler has detected an unusual temperature difference between the pipes, causing it to shut down for safety.

High DIY-safe £120-£350

What to check first

  1. Check if your central heating system pressure is between 1 and 1.5 bar
  2. Ensure all radiator valves are fully open
  3. Try resetting the boiler using the control dial

Parts commonly replaced

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

Related codes

46E

Your boiler has stopped working because it cannot correctly detect the water pressure, often caused by a faulty internal sensor.

High Engineer only £120-190

Parts commonly replaced

  • Water Pressure Sensor
  • Sensor Wiring Loom

Related codes

E02

Your boiler is overheating because the water is not being pumped around the system correctly.

High Engineer only £180-£350

Parts commonly replaced

  • Circulation Pump
  • Pump Capacitor
  • Main Heat Exchanger

Related codes

E03

Your boiler has detected an issue with the sensor that monitors water movement, meaning it cannot safely regulate heat or provide hot water.

High Engineer only £120-220

Parts commonly replaced

  • Flow sensor
  • Wiring harness
  • Main PCB

Related codes

Showing 31–40 of 49
E04

Your boiler's temperature sensor for hot water has stopped working correctly, meaning your taps might not get warm or the water temperature could be inconsistent.

Medium Engineer only £90-160

Parts commonly replaced

  • DHW Temperature Sensor (NTC Thermistor)
  • Wiring harness connecting sensor to PCB

Related codes

E05

Your boiler has stopped working because the fan that removes waste gases is not spinning or communicating correctly with the system.

High Engineer only £180-£350

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Air pressure switch

Related codes

E06

Your boiler has detected that the water inside the heating system is getting too hot and has shut down as a safety precaution.

High Engineer only £90-180

Parts commonly replaced

  • Central Heating (CH) NTC sensor
  • System thermistor
  • Wiring harness
E08

Your boiler has detected that the water pressure in the system is too low to run safely.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (usually a silver flexible hose) underneath the boiler.
  2. Open the one or two valves on the hose slowly until you hear water moving.
  3. Watch the pressure gauge and close the valves once it reaches between 1 and 1.5 bar.

Parts commonly replaced

  • Filling loop
  • Expansion vessel
  • Pressure sensor

Related codes

E09

Your boiler has shut down because it has reached an unsafe temperature and needs to cool down before it can operate again.

High DIY-safe £120-280

What to check first

  1. Check that all radiator valves are fully open to allow water to circulate.
  2. Ensure there is enough water pressure in the system by checking the pressure gauge.
  3. Wait for the boiler to cool down and try pressing the reset button.

Parts commonly replaced

  • Overheat Thermostat
  • Circulation Pump
  • Heat Exchanger

Related codes

E10

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

Medium DIY-safe £0-120

What to check first

  1. Check that the filling loop valves are fully closed
  2. Bleed water from a radiator using a bleed key to reduce pressure
  3. Monitor the pressure gauge until it returns to between 1.0 and 1.5 bar
  4. Reset the boiler if the code persists

Parts commonly replaced

  • Filling loop valve
  • Pressure relief valve
  • Expansion vessel

Related codes

E13

Your boiler’s internal computer has encountered a glitch or a programming fault that is preventing it from running properly.

High DIY-safe £250-450

What to check first

  1. Locate the reset button or dial on the front control panel
  2. Press and hold the reset button for 5 seconds
  3. Wait for the boiler to restart and check if the error code clears

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
E21

Your boiler has detected that the water returning from your radiators is getting too hot, causing the system to shut down for safety.

High DIY-safe £90-180

What to check first

  1. Check that all radiator valves are fully open
  2. Ensure there are no obstructions around the boiler's vents
  3. Reset the boiler to see if the fault clears after the system cools down

Parts commonly replaced

  • CH Return NTC Sensor
  • Pump
  • Main Heat Exchanger (if blocked)

Related codes

E22

Your boiler has detected that the exhaust gases are becoming too hot, causing the system to shut down safely to prevent internal damage.

High Engineer only £120-£280

Parts commonly replaced

  • Flue thermistor
  • Main heat exchanger
  • Pump

Related codes

E23

Your boiler has detected a fault 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 Thermistor
  • Wiring Harness
  • Main PCB

Related codes

Showing 41–49 of 49
E24

Your boiler has detected a problem with the sensor that monitors the water temperature returning from your radiators, preventing it from heating your home correctly.

High Engineer only £90-160

Parts commonly replaced

  • NTC Return Temperature Sensor
  • Wiring Harness

Related codes

E25

Your boiler has detected that the water inside the heating unit has frozen due to extremely low temperatures, preventing it from starting up safely.

High DIY-safe £80-160

What to check first

  1. Turn up the room thermostat and check if the boiler attempts to restart once the house warms up
  2. Thaw the condensate pipe (usually a white plastic pipe outside) using warm water or a heat pack
  3. Keep the heating on a low constant setting during freezing weather to prevent re-freezing

Parts commonly replaced

  • Condensate pipe insulation
  • External pipework

Related codes

E29

Your boiler has detected that the water used for your taps and shower is getting too hot, so it has shut down to prevent damage or scalding.

High Engineer only £90-180

Parts commonly replaced

  • DHW Temperature Sensor (NTC Thermistor)
  • Main Heat Exchanger (if scaled)
  • Diverter Valve

Related codes

E31

Your boiler is having trouble communicating with your external thermostat or heating controls, preventing it from knowing when to turn on.

High DIY-safe £90-250

What to check first

  1. Check that your smart thermostat or wall controller is powered on and has working batteries.
  2. Ensure your internet router is active if you use a Wi-Fi-based heating system.
  3. Reset the boiler by turning the control knob to the 'Reset' position for five seconds.

Parts commonly replaced

  • External Thermostat
  • OpenTherm Bridge/Receiver
  • Main PCB

Related codes

E41

Your boiler has detected that the water leaving the unit and the water returning to it are at very different temperatures, suggesting a circulation problem.

High DIY-safe £120-350

What to check first

  1. Ensure all radiator valves (TRVs) are fully open
  2. Check that the boiler pressure is between 1 and 1.5 bar on the gauge
  3. Gently bleed air from your radiators using a radiator key

Parts commonly replaced

  • Central heating pump
  • NTC thermistor sensors
  • Main heat exchanger (de-scaling)

Related codes

E42

Your boiler has detected an unusual temperature difference between internal parts, suggesting water isn't moving through the system correctly.

High Engineer only £120-£350

Parts commonly replaced

  • Circulation Pump
  • Flow NTC Sensor
  • Return NTC Sensor

Related codes

E43

Your boiler has detected an unusual temperature difference between the pipes, essentially getting confused about how hot the water is at different points in the system.

High DIY-safe £120-250

What to check first

  1. Check that your radiators are bled and all radiator valves are fully open
  2. Ensure your system pressure is topped up to around 1.5 bar
  3. Reset the boiler to see if the error clears

Parts commonly replaced

  • NTC Temperature Sensor
  • Circulation Pump
  • Main PCB

Related codes

E44

Your boiler has detected an unusual temperature difference between internal sensors and has shut down as a safety precaution.

High Engineer only £120-280

Parts commonly replaced

  • NTC thermistor
  • Main heat exchanger decalcitant
  • Pump

Related codes

E46

Your boiler is struggling to accurately measure its internal water pressure, which prevents it from running safely.

High Engineer only £120-190

Parts commonly replaced

  • Water pressure sensor
  • Wiring harness

Related codes