Saunier Duval Themaclassic Plus F30E Fault codes & diagnostics

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

CombiSystem Natural Gas 30 kW 1999-2003 Discontinued
GC Number 41-920-31

Replaced by: ThemaPlus F30 E

Download the Saunier Duval Themaclassic Plus F30E 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.
2 Emergency 32 High 4 Medium

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
41-920-31 Saunier Duval SB30e A 1999–2003

Appliance names and production years are taken from the UK Product Characteristics Database (the SAP/SEDBUK register). Where a GC number is also printed in this model's own manufacturer manual, both sources were checked to agree.

All 38 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 £80-120 Shared across the range

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 Shared across the range

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 Shared across the range

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 Shared across the range

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 Shared across the range

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 Shared across the range

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 Shared across the range

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 Shared across the range

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 Shared across the range

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 Shared across the range

Parts commonly replaced

  • Hot water NTC sensor
  • Wiring harness

Related codes

Showing 11–20 of 38
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 Shared across the range

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 Shared across the range

Parts commonly replaced

  • Return NTC thermistor sensor
  • Wiring harness

Related codes

11

Your boiler's main control panel has lost communication with its internal computer, causing the system to stop working to prevent errors.

High Engineer only £150-300 Shared across the range

Parts commonly replaced

  • Main printed circuit board (PCB)
  • Communication cable (MMI lead)

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 Shared across the range

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 Shared across the range

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 Shared across the range

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 Shared across the range

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 Shared across the range

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 Shared across the range

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 Shared across the range

Parts commonly replaced

  • Main PCB
  • User interface display module
  • Wiring harness

Related codes

Showing 21–30 of 38
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 Shared across the range

Parts commonly replaced

  • NTC temperature sensor
  • Wiring harness
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 Shared across the range

Parts commonly replaced

  • User Interface (PCB)
  • Main Control Board (PCB)
  • Communication 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 Shared across the range

Parts commonly replaced

  • Gas valve
  • Printed Circuit Board (PCB)
  • 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 Shared across the range

Parts commonly replaced

  • Main PCB
  • Interface PCB

Related codes

F1

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

High Engineer only £120-250 Shared across the range

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 Shared across the range

Parts commonly replaced

  • Air pressure switch
  • Flue fan
  • Venturi tube

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 Shared across the range

Parts commonly replaced

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

Related codes

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 Shared across the range

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 Shared across the range

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 Shared across the range

Parts commonly replaced

  • NTC sensor
  • Wiring loom

Related codes

Showing 31–38 of 38
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 Shared across the range

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 Shared across the range

Parts commonly replaced

  • Main PCB
  • Wiring harness

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 Shared across the range

Parts commonly replaced

  • Main PCB

Related codes

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 Shared across the range

Parts commonly replaced

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

Related codes

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 Shared across the range

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 Shared across the range

Parts commonly replaced

  • Main PCB
  • Wiring harness
  • Display interface
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 Shared across the range

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 Shared across the range

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