Saunier Duval Thema F 30 E Plus Fault codes & diagnostics

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

Combi Natural Gas 30 kW 2006-2010 Discontinued

Replaced by: ThemaPlus F 30 E

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4 Emergency 50 High 5 Medium
Just want the most common Saunier Duval Thema F 30 E Plus faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 59 documented codes

Tap any card for details

0.5bar

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 (usually a silver braided hose with one or two valves underneath the boiler)
  2. Slowly open the valve(s) to let mains water enter the system
  3. Monitor the pressure gauge until the needle reaches the green zone between 1.0 and 1.5 bar, then turn the valve(s) firmly off

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Expansion vessel
Full explanation for 0.5bar
01

Your boiler is failing to light because it is not receiving gas or cannot sense a flame, meaning you currently have no heating or hot water.

High Engineer only £120-250

Parts commonly replaced

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

Related codes

Full explanation for 01
02

Your boiler is failing to clear combustion gases, so it has safely shut down to prevent any risk of fumes entering your home.

Emergency Engineer only £150-300

Parts commonly replaced

  • Air pressure switch
  • Flue fan
  • Wiring harness

Related codes

Full explanation for 02
2.7bar

Your boiler's internal water pressure is currently too high, which means the system is holding more water than it is designed to manage safely.

High DIY-safe £80-150

What to check first

  1. Locate a radiator in your home with a bleed valve.
  2. Place a cloth or small container under the valve.
  3. Use a radiator key to slowly release air and then water until the pressure gauge on the front of the boiler drops back to between 1.0 and 1.5 bar.

Parts commonly replaced

  • Pressure relief valve
  • Filling loop
  • Expansion vessel
Full explanation for 2.7bar
03

Your boiler is struggling to clear exhaust gases effectively, meaning it has shut down as a safety precaution to prevent dangerous fumes from staying inside.

Emergency Engineer only £150-350

Parts commonly replaced

  • Air pressure switch
  • Flue fan
  • Venturi
  • PCB

Related codes

Full explanation for 03
04

Your boiler has failed to light because it cannot detect a flame, meaning you currently have no heating or hot water.

High Engineer only £120-250

Parts commonly replaced

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

Related codes

Full explanation for 04
05

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 sensor
  • Primary heat exchanger
  • Pump

Related codes

Full explanation for 05
06

Your boiler is currently unable to read the temperature of the water used for your radiators, so it has safely shut itself down to prevent overheating.

High Engineer only £120-200

Parts commonly replaced

  • NTC Temperature Sensor
  • Wiring harness

Related codes

Full explanation for 06
07

Your boiler is struggling to accurately measure the temperature of the water used for your taps and shower, so it has stopped providing hot water to prevent overheating.

Medium Engineer only £120-220

Parts commonly replaced

  • Domestic Hot Water (DHW) NTC Temperature Sensor

Related codes

Full explanation for 07
08

Your boiler is having trouble reading the temperature of the internal store of hot water, which may mean your hot water tap takes slightly longer to heat up or isn't as consistent.

Medium Engineer only £150-250

Parts commonly replaced

  • NTC Temperature Sensor
  • Wiring Harness

Related codes

Full explanation for 08
Showing 11–20 of 59
09

Your boiler is struggling to accurately detect the water level inside the system, which is preventing it from heating your home or water.

High Engineer only £150-250

Parts commonly replaced

  • Water pressure sensor
  • Wiring harness

Related codes

Full explanation for 09
10

Your boiler is currently unable to read the water temperature returning from your radiators, so it has stopped heating them to prevent potential damage.

High Engineer only £120-200

Parts commonly replaced

  • NTC sensor
  • Wiring harness

Related codes

Full explanation for 10
12

Your boiler is struggling to communicate with the control panel or thermostat, meaning it cannot receive instructions to provide heating or hot water.

High Engineer only £150-300

Parts commonly replaced

  • User interface communication cable
  • Main printed circuit board (PCB)
  • External thermostat/control unit

Related codes

Full explanation for 12
13

Your boiler's internal computer is experiencing a communication error, meaning it can no longer safely control the system or manage heating and hot water.

High Engineer only £250-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
Full explanation for 13
14

Your boiler has detected that the water inside the unit is getting dangerously hot and has shut itself down to prevent damage.

High Engineer only £150-300

Parts commonly replaced

  • NTC Temperature Sensor
  • Circulation Pump
  • Main Heat Exchanger

Related codes

Full explanation for 14
15

Your boiler is struggling to control its internal gas flow, which is preventing it from lighting safely.

High Engineer only £180-350

Parts commonly replaced

  • Gas valve
  • Main PCB

Related codes

Full explanation for 15
16

Your boiler has detected a failure in the system that controls the flow of gas, meaning it is no longer safe to operate and has shut down to prevent a risk.

Emergency Engineer only £180-350

Parts commonly replaced

  • Gas valve actuator
  • Main PCB
  • Wiring harness

Related codes

Full explanation for 16
17

Your boiler is struggling because the electricity supply feeding it is too weak or unstable to function correctly.

High Engineer only £100-250

Parts commonly replaced

  • Main circuit board (PCB)
  • Power supply surge protection fuse

Related codes

Full explanation for 17
18

Your boiler's electronic display is experiencing a communication error, meaning the main controls are currently unable to operate the heating and hot water correctly.

High Engineer only £150-300

Parts commonly replaced

  • User interface circuit board
  • Wiring harness
  • Main PCB

Related codes

Full explanation for 18
19

Your boiler has lost the signal from the sensor that monitors the temperature of the water flowing to your radiators, causing it to stop working for safety reasons.

High Engineer only £120-220

Parts commonly replaced

  • Central heating NTC temperature sensor
  • Wiring harness
Full explanation for 19
Showing 21–30 of 59
20

Your boiler is struggling to communicate with its control panel because they are not properly matched or connected, preventing the unit from starting.

High Engineer only £120-250

Parts commonly replaced

  • User interface board
  • PCB
  • Wiring harness
Full explanation for 20
E01

Your boiler has tried to ignite but failed to detect a flame, meaning your heating and hot water will not work.

High DIY-safe £100-350

What to check first

  1. Check that your gas emergency control valve is in the 'on' position
  2. Verify if other gas appliances in your home, like a hob, are working correctly
  3. Press and hold the reset button (often marked with a flame or 'R') for 5 seconds

Parts commonly replaced

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

Related codes

Full explanation for E01
E02

Your boiler has stopped working because it cannot confirm that waste gases are being safely vented out of the flue.

High Engineer only £120-240

Parts commonly replaced

  • Air Pressure Switch
  • Venturi Tube
  • Fan Assembly

Related codes

Full explanation for E02
E03

Your boiler has detected a problem with how it disposes of exhaust fumes or takes in fresh air, causing it to shut down for safety.

High Engineer only £100-240

Parts commonly replaced

  • Air Pressure Switch
  • Venturi Tube
  • Fan Assembly

Related codes

Full explanation for E03
E05

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

High DIY-safe £120-£250

What to check first

  1. Ensure all radiator valves are fully open to allow water to circulate.
  2. Wait 20 minutes for the boiler to cool down completely.
  3. Press the 'Reset' button on the front control panel to clear the error.

Parts commonly replaced

  • Overheat Thermostat (Limit Statutory Sensor)
  • Circulation Pump
  • Heat Exchanger (de-scaling)

Related codes

Full explanation for E05
E06

Your boiler's temperature sensor responsible for heating your radiators is either faulty or has a loose connection, preventing the system from warming up properly.

High Engineer only £90-160

Parts commonly replaced

  • Central heating flow NTC thermistor
  • Wiring harness connector

Related codes

Full explanation for E06
E09

Your boiler has stopped working because it cannot correctly detect the water pressure, even if there is plenty of water in the system.

High Engineer only £120-£190

Parts commonly replaced

  • Water pressure sensor
  • Wiring harness

Related codes

Full explanation for E09
E12

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

Medium Engineer only £90-160

Parts commonly replaced

  • DHW Thermistor (NTC Sensor)
  • Thermistor wiring harness
Full explanation for E12
E13

Your boiler's internal computer has developed a fault and can no longer control the heating or hot water functions.

High Engineer only £250-£450

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
  • Wiring harness connections

Related codes

Full explanation for E13
E14

Your boiler has detected an electrical issue with the part that controls the gas supply, meaning it cannot light safely.

High Engineer only £180-350

Parts commonly replaced

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

Related codes

Full explanation for E14
Showing 31–40 of 59
E15

Your boiler's gas valve control motor is struggling to adjust properly, which prevents it from heating your home or water correctly.

High Engineer only £180-320

Parts commonly replaced

  • Gas valve stepper motor
  • Complete gas valve assembly
  • PCB

Related codes

Full explanation for E15
E16

Your boiler is still detecting a flame even though it has commanded the burner to shut down, which is a safety concern that prevents it from restarting.

High Engineer only £120-350

Parts commonly replaced

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

Related codes

Full explanation for E16
E19

Your boiler has lost connection with a temperature sensor that monitors the heating system, meaning it cannot safely determine how hot the water is getting.

High Engineer only £90-160

Parts commonly replaced

  • Central heating NTC sensor
  • Wiring harness connector

Related codes

Full explanation for E19
E20

Your boiler's internal computer boards are having trouble communicating with each other, meaning the system cannot safely operate.

High Engineer only £180-350

Parts commonly replaced

  • Main PCB
  • Interface PCB
  • Display Board

Related codes

Full explanation for E20
E21

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

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (usually a silver flexible hose) underneath the boiler.
  2. Slowly open the one or two taps on the loop until you hear water flowing.
  3. Watch the pressure gauge until it reaches between 1.0 and 1.5 bar, then turn the taps off securely.

Parts commonly replaced

  • Filling loop valves
  • Expansion vessel
  • Pressure sensor

Related codes

Full explanation for E21
F (High system water pressure)

Your boiler's internal water pressure is currently too high, which means it has automatically shut down to prevent damage to the system.

Medium DIY-safe £80-150

What to check first

  1. Locate a radiator in your home that is easily accessible.
  2. Place a cloth or small container under the radiator bleed valve.
  3. Open the bleed valve carefully to release water until the pressure gauge on the front of the boiler drops to between 1.0 and 1.5 bar.

Parts commonly replaced

  • Pressure relief valve
  • Filling loop
  • Pressure sensor
Full explanation for F (High system water pressure)
F (Low system water pressure)

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

High DIY-safe £0-80

What to check first

  1. Locate the external filling loop, usually situated underneath the boiler casing.
  2. Open the filling valve(s) slowly to allow mains water into the system.
  3. Keep watching the pressure gauge until it reaches between 1.0 and 1.5 bar, then firmly close the valve(s).

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Pressure sensor
Full explanation for F (Low system water pressure)
F0

Your boiler is struggling to read its own internal water temperature, so it has shut down as a precaution to prevent overheating.

High Engineer only £120-220

Parts commonly replaced

  • NTC Sensor
  • Wiring harness

Related codes

Full explanation for F0
F1

Your boiler has tried to start but failed to light the flame properly, which means it has safely shut itself down to prevent gas from building up.

High Engineer only £120-250

Parts commonly replaced

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

Related codes

Full explanation for F1
Showing 41–50 of 59
F2

Your boiler is struggling to breathe because it cannot effectively vent gases outside, so it has safely shut down to prevent any unsafe buildup.

High Engineer only £150-300

Parts commonly replaced

  • Fan unit
  • Air pressure switch
  • Venturi assembly
  • Printed Circuit Board

Related codes

Full explanation for F2
F3

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

High Engineer only £120-250

Parts commonly replaced

  • NTC Temperature Sensor
  • Pump
  • Primary Heat Exchanger
  • PCB

Related codes

Full explanation for F3
F4

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

High Engineer only £120-200

Parts commonly replaced

  • Domestic hot water NTC thermistor
  • Wiring harness

Related codes

Full explanation for F4
F5

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

High Engineer only £120-250

Parts commonly replaced

  • Overheat thermostat
  • NTC sensor
  • Pump
  • Primary heat exchanger

Related codes

Full explanation for F5
F6

Your boiler has lost the ability to accurately measure the temperature of the water circulating through your heating system, so it has shut down to prevent overheating.

High Engineer only £120-220

Parts commonly replaced

  • NTC Temperature Sensor
  • Wiring Harness

Related codes

Full explanation for F6
F7

Your boiler is struggling to accurately detect the temperature of your hot water supply, so it has safely stopped heating the water to prevent it from getting too hot.

Medium Engineer only £120-220

Parts commonly replaced

  • Domestic Hot Water NTC Thermistor
  • Wiring harness

Related codes

Full explanation for F7
F8

Your boiler has lost the ability to accurately measure the temperature of the water returning to it, so it has purposefully turned itself off to prevent overheating.

High Engineer only £120-200

Parts commonly replaced

  • Return NTC thermistor
  • Wiring harness

Related codes

Full explanation for F8
F9

Your boiler is struggling to accurately measure the water pressure inside the system, which is preventing it from firing up safely.

High Engineer only £150-250

Parts commonly replaced

  • Water pressure sensor
  • Wiring harness
Full explanation for F9
F11

Your boiler's electronic brains are struggling to talk to each other, which means the system cannot safely manage your heating and hot water.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB
  • Interface PCB
  • Wiring loom

Related codes

Full explanation for F11
F12

Your boiler's electronic control panel and internal circuit board are struggling to talk to each other, preventing the boiler from starting.

High Engineer only £150-350

Parts commonly replaced

  • Main PCB
  • User Interface board
  • Communication cable

Related codes

Full explanation for F12
Showing 51–59 of 59
F13

Your boiler's central control computer has encountered a critical internal error and can no longer safely operate the system.

High Engineer only £250-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)

Related codes

Full explanation for F13
F14

Your boiler has detected an issue with the valve that regulates the gas supply, meaning it cannot ignite to provide heat or hot water.

High Engineer only £180-350

Parts commonly replaced

  • Gas valve
  • Printed Circuit Board (PCB)

Related codes

Full explanation for F14
F15

Your boiler is struggling to operate the internal valve that directs heat to your taps or radiators, meaning you likely have no hot water or heating.

High Engineer only £180-300

Parts commonly replaced

  • Stepper motor
  • Diverter valve assembly

Related codes

Full explanation for F15
F16

Your boiler is struggling because it senses a flame inside even when it is supposed to be turned off, which is a safety lockout preventing it from firing up again.

Emergency Engineer only £150-300

Parts commonly replaced

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

Related codes

Full explanation for F16
F17

Your boiler is struggling because the electricity supply it is receiving is weaker than it needs to operate correctly.

High Engineer only £120-250

Parts commonly replaced

  • Printed circuit board
  • Power supply module

Related codes

Full explanation for F17
F19

Your boiler has lost the signal from a temperature sensor that monitors the heating water, causing it to shut down to prevent overheating.

High Engineer only £120-220

Parts commonly replaced

  • NTC thermistor
  • Wiring harness

Related codes

Full explanation for F19
F20

Your boiler's control panel and its internal brain are not talking to each other correctly, which means the system cannot safely operate.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB
  • User Interface Module
Full explanation for F20
F21

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

High DIY-safe £80-150

What to check first

  1. Locate the external filling loop, which is usually a flexible silver braided hose connecting two pipes under the boiler.
  2. Open the valves at both ends of the loop to allow mains water into the heating 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. Close both valves tightly and remove the filling loop if required by your specific model setup.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Pressure sensor
Full explanation for F21
Water pressure

Your boiler has detected that the amount of water circulating through your heating system is too low, so it has safely stopped working to prevent any damage.

High DIY-safe

What to check first

  1. Locate the filling loop, which is usually a small silver braided hose with one or two valves located underneath the boiler.
  2. Slowly open the valve(s) to let mains water into the system until the pressure gauge on the front of the boiler reads between 1.0 and 1.5 bar.
  3. Close the valve(s) tightly to stop the flow; the boiler should then automatically restart.

Parts commonly replaced

  • Pressure relief valve
  • Expansion vessel
  • Pressure sensor
Full explanation for Water pressure