Saunier Duval Thema F 30 E Plus Fault codes & diagnostics

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

CombiSystem Natural Gas 30 kW 2001 onwards Discontinued
GC Numbers 47-920-3647-920-3747-920-3841-920-45

Replaced by: ThemaPlus F 30 E

Download the Saunier Duval Thema F 30 E Plus 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.
3 Emergency 19 High 1 Medium
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
47-920-37 Thema Classic F24E Plus 2001–present
47-920-38 Thema Classic F30E Plus 2002–present
41-920-45 Thema Classic F30E SB 2002–present
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 23 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
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
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
Showing 11–20 of 23
11

Your boiler's main control panel is unable to communicate with the internal computer, causing the system to stop working entirely.

High Engineer only £150-300

Parts commonly replaced

  • MMI connection cable
  • Main PCB
  • Interface board

Related codes

Full explanation for 11
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
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
Showing 21–23 of 23
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
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
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