Saunier Duval Themaclassic Plus F30E Fault codes & diagnostics

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

Combi Natural Gas 30 kW 2005-2010 Discontinued

Replaced by: ThemaPlus F30 E

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3 Emergency 49 High 5 Medium

All 57 documented codes

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0.5bar

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

High DIY-safe £80-120

What to check first

  1. Locate the filling loop, which is usually a metal braided hose underneath the boiler.
  2. Open the two valves on the filling loop to allow cold mains water into the system.
  3. Watch the pressure gauge on the front of the boiler until it reaches 1.5 bar, then firmly close both valves.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Expansion vessel
01

Your boiler is failing to light because it cannot detect a flame or is not receiving a gas supply, causing it to shut down for safety.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Printed Circuit Board (PCB)
02

Your boiler has detected an issue with its internal ventilation system, meaning it has safely shut down because it cannot clear exhaust gases properly.

High Engineer only £150-300

Parts commonly replaced

  • Air pressure switch
  • Flue fan
  • Venturi tube

Related codes

2.7bar

Your boiler's internal water pressure is currently too high, which can put unnecessary strain on the system's internal safety components.

High DIY-safe £80-120

What to check first

  1. Locate a radiator in your home that is easily accessible
  2. Use a radiator bleed key to gently open the bleed valve
  3. Release a small amount of water into a cloth or container until the pressure gauge on the boiler drops to between 1.0 and 1.5 bar

Parts commonly replaced

  • Pressure Relief Valve (PRV)
  • Expansion Vessel
03

Your boiler is struggling to clear exhaust gases or draw in fresh air properly, so it has safely shut itself down to prevent unsafe operation.

High Engineer only £150-350

Parts commonly replaced

  • Air pressure switch
  • Flue fan assembly
  • Venturi
04

Your boiler is failing to light because it is not receiving gas or cannot sense the flame.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Main PCB

Related codes

05

Your boiler has detected that it has become too hot and has automatically shut down to prevent damage to its internal systems.

High Engineer only £120-250

Parts commonly replaced

  • NTC Sensor
  • Primary Heat Exchanger
  • Pump
  • Heating Circuit Filter

Related codes

06

Your boiler's temperature sensor is failing to provide accurate readings, which has caused the system to stop heating your home as a safety precaution.

High Engineer only £120-220

Parts commonly replaced

  • NTC Flow Sensor
  • Wiring harness / Connection loom

Related codes

07

Your boiler is struggling to detect the temperature of the water it is trying to heat for your taps and shower, so it has turned off that function to prevent any issues.

Medium Engineer only £120-200

Parts commonly replaced

  • Domestic Hot Water (DHW) NTC Sensor
  • Wiring harness

Related codes

08

Your boiler is struggling to accurately measure the temperature of the water it keeps ready for your taps, which may cause your hot water to fluctuate in temperature or stop working entirely.

Medium Engineer only £120-200

Parts commonly replaced

  • Hot water NTC sensor
  • Wiring harness

Related codes

Showing 11–20 of 57
09

Your boiler is struggling to accurately detect the water level inside the system, which is preventing it from safely starting up to provide heating or hot water.

High Engineer only £120-220

Parts commonly replaced

  • Water pressure sensor
  • Wiring harness

Related codes

10

Your boiler is having trouble reading the temperature of the water returning from your radiators, which means it has stopped heating your home to prevent potential overheating.

High Engineer only £120-200

Parts commonly replaced

  • Return NTC thermistor sensor
  • Wiring harness

Related codes

12

Your boiler is having a communication breakdown with its control panel, meaning it cannot receive your temperature or setting instructions.

Medium Engineer only £150-300

Parts commonly replaced

  • Control board (PCB)
  • Interface display module
  • Connecting wiring harness

Related codes

13

Your boiler's electronic controller has encountered an internal error and has shut down for safety, meaning you currently have no heating or hot water.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB (Printed Circuit Board)

Related codes

14

Your boiler has detected that the water inside the heating system has become too hot and has automatically shut down to prevent damage.

High Engineer only £120-250

Parts commonly replaced

  • NTC secondary sensor
  • Primary flow sensor
  • Heating pump

Related codes

15

Your boiler is currently unable to control the flow of gas needed to ignite the flame, so it has safely shut down to prevent any issues.

High Engineer only £180-300

Parts commonly replaced

  • Stepper motor
  • Gas valve assembly
  • PCB

Related codes

16

Your boiler has detected an issue with the valve that controls the supply of gas, meaning it has safely shut itself down to prevent any risk.

Emergency Engineer only £150-300

Parts commonly replaced

  • Gas valve
  • Printed circuit board (PCB)

Related codes

17

Your boiler is struggling because the electricity supply it is receiving is too weak or unstable to run safely.

High Engineer only £120-250

Parts commonly replaced

  • Printed circuit board (PCB)
  • Electrical wiring harness

Related codes

18

Your boiler's electronic control panel is experiencing a communication error, which means it cannot process your settings or send instructions to the heating system.

High Engineer only £150-300

Parts commonly replaced

  • Main PCB
  • User interface display module
  • Wiring harness

Related codes

19

Your boiler has lost its connection to the heat sensor that measures the temperature of the water circulating to your radiators, so it has shut down to prevent overheating.

High Engineer only £120-220

Parts commonly replaced

  • NTC temperature sensor
  • Wiring harness
Showing 21–30 of 57
20

Your boiler's electronic control panel is not communicating correctly with the main internal computer, which is preventing the system from running.

High Engineer only £150-300

Parts commonly replaced

  • User Interface (PCB)
  • Main Control Board (PCB)
  • Communication Wiring Harness

Related codes

E01

Your boiler is failing to light the internal flame, which means it has automatically shut down to prevent gas from building up safely.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Printed Circuit Board
E02

Your boiler has detected an issue with its internal ventilation system and has shut down to ensure it operates safely.

High Engineer only £150-250

Parts commonly replaced

  • Air pressure switch
  • Flue fan
  • Venturi
E03

Your boiler is struggling to clear exhaust gases safely, so it has stopped working to prevent any risk.

High Engineer only £120-250

Parts commonly replaced

  • Air pressure switch
  • Flue fan
  • Venture pipe

Related codes

E05

Your boiler has detected that it is running too hot and has automatically switched itself off to prevent internal damage.

High Engineer only £120-250

Parts commonly replaced

  • Overheat thermostat
  • NTC thermistor
  • Primary heat exchanger
  • Pump
E06

Your boiler has lost the ability to accurately measure the temperature of the water being sent to your radiators, so it has shut down to prevent overheating.

High Engineer only £120-220

Parts commonly replaced

  • Central heating NTC thermistor
  • Wiring harness

Related codes

E09

Your boiler is struggling to accurately read how much water is inside its system, which is preventing it from safely starting up the heating or hot water.

High Engineer only £150-250

Parts commonly replaced

  • Water pressure sensor
  • Wiring harness
E12

Your boiler is having trouble sensing the temperature of your hot water, which means it will likely stop producing hot water until the sensor is fixed.

High Engineer only £120-200

Parts commonly replaced

  • DHW NTC sensor
  • Wiring harness

Related codes

E13

Your boiler's internal computer is experiencing a communication error and is unable to safely control the heating and hot water system.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB
  • Wiring harness

Related codes

E14

Your boiler has detected a problem with the internal mechanism that controls the gas supply, meaning it cannot safely start up to provide heating or hot water.

High Engineer only £180-350

Parts commonly replaced

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

Related codes

Showing 31–40 of 57
E15

Your boiler is struggling to operate the internal valve that directs water between your heating and hot water, which may prevent the system from working correctly.

High Engineer only £180-300

Parts commonly replaced

  • Diverter valve motor
  • Diverter valve cartridge

Related codes

E16

Your boiler is struggling to confirm that the flame has properly extinguished after it has finished heating, which prevents it from safely starting again.

High Engineer only £150-250

Parts commonly replaced

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

Related codes

E19

Your boiler has lost the signal from the sensor that monitors your heating temperature, causing the system to stop working as a precaution.

High Engineer only £120-220

Parts commonly replaced

  • NTC sensor
  • Wiring harness

Related codes

E20

Your boiler's electronic brains are failing to communicate with each other because they are not compatible, meaning the system cannot safely operate.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB
  • Interface PCB

Related codes

E21

Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.

High DIY-safe £80-£120

What to check first

  1. Locate the filling loop (a silver flexi-hose) connected to the underside of the boiler.
  2. Open the small tap or valve on the filling loop to allow cold mains water into the heating system.
  3. Monitor the pressure gauge on the front of the boiler until the needle reaches the green zone (typically 1.0 to 1.5 bar).
  4. Close the valve tightly and ensure the boiler resets itself.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Pressure sensor
F0

Your boiler is struggling to accurately measure the temperature of the water flowing through the system, so it has shut down to prevent potential damage.

High Engineer only £120-200

Parts commonly replaced

  • NTC Flow Sensor
  • Wiring harness

Related codes

F1

Your boiler is failing to light the internal flame needed to produce heat or hot water.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB

Related codes

F2

Your boiler is failing to clear combustion gases properly, so it has safely shut itself down to prevent any risk.

High Engineer only £120-250

Parts commonly replaced

  • Air pressure switch
  • Flue fan
  • Venturi tube

Related codes

F3

Your boiler is struggling to clear exhaust gases out of the flue, so it has safely shut itself down to prevent fumes from building up.

High Engineer only £150-300

Parts commonly replaced

  • Air pressure switch
  • Flue fan unit
  • Venture tube or silicone sensing tubes

Related codes

F4

Your boiler is trying to start but failing to light the flame, so it has shut down for safety to prevent gas from building up.

High Engineer only £120-250

Parts commonly replaced

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

Related codes

Showing 41–50 of 57
F5

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

High Engineer only £120-250

Parts commonly replaced

  • NTC Temperature Sensor
  • Pump
  • Primary Heat Exchanger

Related codes

F6

Your boiler is currently unable to detect that water is circulating properly through your heating system, which has caused it to shut down to prevent damage.

High Engineer only £150-250

Parts commonly replaced

  • Flow sensor
  • Wiring harness
  • PCB

Related codes

F7

Your boiler is struggling to accurately detect the temperature of your hot water, which means it may fail to provide hot water or heat it correctly.

Medium Engineer only £120-200

Parts commonly replaced

  • NTC sensor
  • Wiring loom

Related codes

F8

Your boiler is having trouble detecting the temperature of the water stored for instant hot water, which may lead to inconsistent tap temperatures or the boiler struggling to start.

Medium Engineer only £120-220

Parts commonly replaced

  • NTC sensor
  • Wiring harness
  • PCB

Related codes

F9

Your boiler is struggling to accurately measure the water pressure inside the system, which causes it to shut down to prevent potential damage.

High Engineer only £150-250

Parts commonly replaced

  • Water pressure sensor
  • Wiring harness
F11

The internal computer board that controls your boiler is struggling to talk to the other components, causing the system to shut down for safety.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB
  • Wiring harness

Related codes

F12

Your boiler's electronic control panel is experiencing a communication error, which prevents the system from receiving instructions to heat your home or water.

High Engineer only £200-350

Parts commonly replaced

  • User interface PCB
  • Main control PCB

Related codes

F13

The internal computer that controls your boiler has experienced a technical error, meaning the system cannot run safely or effectively.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB

Related codes

F14

Your boiler is struggling to control the internal fuel supply, which means it will remain locked out and unable to provide heat or hot water until a professional inspects it.

Emergency Engineer only £150-300

Parts commonly replaced

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

Related codes

F15

Your boiler is having trouble controlling the flow of gas necessary to ignite the flame, meaning it will likely stop providing heating and hot water.

High Engineer only £150-250

Parts commonly replaced

  • Gas valve assembly
  • Wiring harness

Related codes

Showing 51–57 of 57
F16

Your boiler is detecting a flame inside even when it is supposed to be turned off, which is a safety issue that requires the unit to shut down to prevent potential gas build-up.

Emergency Engineer only £120-250

Parts commonly replaced

  • Gas valve
  • Printed Circuit Board (PCB)
  • Flame sensing electrode

Related codes

F17

Your boiler has detected that the incoming electricity supply is too weak or unstable to operate safely.

High Engineer only £120-250

Parts commonly replaced

  • Printed circuit board (PCB)
  • Voltage regulator
F19

Your boiler has lost the signal it needs to detect the flow of water, stopping it from heating your home or water.

High Engineer only £120-220

Parts commonly replaced

  • Flow sensor
  • Wiring harness
  • PCB

Related codes

F20

Your boiler's electronic control panel is not communicating properly with the internal computer system, resulting in a system shutdown.

High Engineer only £150-300

Parts commonly replaced

  • Main PCB
  • Wiring harness
  • Display interface
F21

Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.

High DIY-safe £80-150

What to check first

  1. Locate the filling loop, which is usually a small silver braided hose or a pair of taps underneath the boiler.
  2. Open the valves slowly to allow mains water into the system while watching the pressure gauge on the front of the boiler.
  3. Stop filling once the needle reaches the green zone, typically between 1.0 and 1.5 bar, then tightly close both valves.

Parts commonly replaced

  • Pressure relief valve
  • Pressure sensor
  • Expansion vessel
Ignition fault

Your boiler has failed to light the flame needed for heating and hot water, so it has safely shut itself down.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB

Related codes

Water pressure

Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.

High DIY-safe £80-150

What to check first

  1. Locate the filling loop (a flexible metal hose) connected to the pipework underneath your boiler.
  2. Open the valves at both ends of the filling loop slowly to let water enter the system.
  3. Watch the pressure gauge on the front of the boiler until the needle reaches the green zone (typically between 1.0 and 1.5 bar).
  4. Once the pressure is correct, firmly close both valves and ensure the loop is disconnected if it is a removable type.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Pressure sensor