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 Number 47-920-36

Replaced by: ThemaPlus F 30 E

Choose your boiler type

The Thema F 30 E Plus range comes in 3 types

Pick the one you have. The fault codes, GC numbers and manual differ by type.

F24E Plus 22 codes · 1 GC number F30E Plus 22 codes · 1 GC number F30E SB 19 codes · 1 GC number
Each model has its own manual A family spans several manuals, one per model or generation. Pick your model above and its page has the manual its fault codes were read from.

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 18 High 2 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 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 Shared across the Thema Classic range

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 Shared across the Thema Classic range

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 Shared across the Thema Classic range

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 Shared across the Thema Classic range

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 Shared across the Thema Classic range

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 Shared across the Thema Classic range

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 Shared across the Thema Classic range

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 Shared across the Thema Classic range

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 Shared across the Thema Classic range

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 Shared across the Thema Classic range

Parts commonly replaced

  • NTC Temperature Sensor
  • Wiring Harness

Related codes

Full explanation for 08
Showing 11–20 of 23
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 Shared across the Thema Classic range

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 Shared across the Thema Classic range

Parts commonly replaced

  • NTC sensor
  • Wiring harness

Related codes

Full explanation for 10
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 Shared across the Thema Classic range

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 Shared across the Thema Classic range

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 Shared across the Thema Classic range

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 Shared across the Thema Classic range

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 Shared across the Thema Classic range

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 Shared across the Thema Classic range

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 Shared across the Thema Classic range

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 Shared across the Thema Classic range

Parts commonly replaced

  • User interface circuit board
  • Wiring harness
  • Main PCB

Related codes

Full explanation for 18
Showing 21–23 of 23
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 Shared across the Thema Classic range

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 Shared across the Thema Classic range

Parts commonly replaced

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

Your boiler has failed to light its flame, meaning you currently have no heating or hot water.

High Engineer only £150-300 Shared across the Thema Classic range

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB

Related codes

Full explanation for F