Saunier Duval Ecosy 24E Fault codes & diagnostics

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

Combi Natural Gas 24 kW 1997-2004 Discontinued

Replaced by: Thema Classic

This boiler uses LED flash patterns

Count the flashes in one repeating group before the pause. That number is your fault code. Do not reset until you have noted it. How to read fault codes →

Severity at a glance

Each cell = one fault code. Hover to identify.
1 Emergency 44 High 1 Medium

All 46 documented codes

Tap any card for details

9 25 blinking

Your boiler has stopped working because it cannot move the hot water around your system effectively, so it has shut down to protect itself.

High Engineer only £150-300

Parts commonly replaced

  • Central heating pump
  • Flow sensor
  • Printed Circuit Board
0 then 8

Your boiler has shut down because a waste water pipe is blocked, preventing it from safely draining away the liquid produced during normal operation.

High Engineer only £90-180

Parts commonly replaced

  • Condensate siphon
  • Condensate discharge pipework
00.

Your boiler has detected a signal suggesting a flame is burning when it shouldn't be, which has caused it to shut down for safety reasons.

Emergency Engineer only £180-350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Flame rectification electrode
  • Wiring harness
1 2

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

High DIY-safe £0-£120

What to check first

  1. Locate the filling loop (typically a silver braided hose with one or two valves underneath the boiler).
  2. Slowly open the valve(s) to allow cold mains water into the system until the pressure gauge reads between 1.0 and 1.5 bar.
  3. Close the valve(s) tightly to stop the flow and ensure no water is leaking.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Pressure sensor
1 8

Your boiler has detected that the water inside the unit is dangerously overheated, so it has safely shut itself down to prevent damage.

High Engineer only £150-250

Parts commonly replaced

  • NTC Temperature Sensor
  • Pump
  • Primary Heat Exchanger
1 9

Your boiler has shut down because it thinks the water returning to the system is dangerously hot, which could indicate a flow blockage or a faulty sensor.

High Engineer only £120-250

Parts commonly replaced

  • NTC Return Thermistor
  • Central Heating Pump
  • Primary Heat Exchanger
1 then 2

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

High DIY-safe £0-£120

What to check first

  1. Locate the external filling loop, usually a silver braided hose with one or two valves located underneath the boiler.
  2. Open the valve(s) slowly to allow water into the system until the pressure gauge needle rises to between 1.0 and 1.5 bar.
  3. Close the valve(s) firmly and ensure there is no water dripping from the connection.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Expansion vessel
02

Your boiler is failing to ignite because it cannot detect a flame, which is often caused by air trapped in the gas supply.

High Engineer only £120-£250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB

Related codes

2 5

Your boiler is shutting down because the water inside is heating up much faster than the system can move it around, which suggests a blockage or a pump issue.

High Engineer only £150-300

Parts commonly replaced

  • Circulation pump
  • Flow thermistor
  • Primary heat exchanger
2 8

Your boiler has stopped working because it cannot detect that the internal air extraction fan is running properly.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Wiring harness
Showing 11–20 of 46
2 9

Your boiler has detected that the internal fan is not spinning, so it has safely shut down to prevent the system from operating incorrectly.

High Engineer only £180-300

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Wiring harness
02.

Your boiler has attempted to start, but it cannot detect a flame, so it has safely shut itself down to prevent gas from building up.

High Engineer only £150-300

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Printed Circuit Board (PCB)
  • Flame rectification probe
03.

Your boiler's main internal computer has developed a malfunction and can no longer control the heating process safely.

High Engineer only £250-£450

Parts commonly replaced

  • Automatic Control Module
  • Printed Circuit Board (PCB)

Related codes

04

Your boiler has lost its electricity supply, likely caused by a power cut or a tripped fuse.

High DIY-safe £80-150

What to check first

  1. Check your home's fuse box or consumer unit to see if the switch for the boiler has tripped.
  2. Ensure the fused spur switch located near the boiler is turned to the on position.
  3. Wait a few minutes to see if the boiler automatically resets once power is restored.

Parts commonly replaced

  • Main printed circuit board
  • Power supply cable
  • Fused spur switch

Related codes

04.

Your boiler has stopped because it has lost its electrical connection, likely due to a tripped switch or a power outage in your home.

High DIY-safe £80-150

What to check first

  1. Check your home's fuse box or consumer unit to see if the boiler's circuit breaker has tripped.
  2. Ensure the fused spur switch located near the boiler is turned on.
  3. Check that the boiler display has regained power after resetting any tripped switches.

Parts commonly replaced

  • PCB (Printed Circuit Board)
  • Wiring harness
  • Fused spur
05.

Your boiler's internal computer is experiencing a critical error and cannot safely operate the heating or hot water system.

High Engineer only £250-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Control Module
06.

Your boiler’s internal computer has encountered a critical error and is unable to manage the system safely, causing the boiler to shut down.

High Engineer only £250-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Control Module

Related codes

07.

Your boiler's internal computer has encountered a critical error preventing it from operating safely and correctly.

High Engineer only £250-450

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring loom

Related codes

08

Your boiler is failing to start because it cannot confirm that the internal fan is effectively clearing exhaust gases, preventing it from safely igniting.

High Engineer only £150-300

Parts commonly replaced

  • Air pressure switch
  • Flue fan unit
  • Venturi assembly
08.

Your boiler is failing to start because it cannot confirm that the internal fan is moving air correctly to safely vent exhaust fumes.

High Engineer only £150-300

Parts commonly replaced

  • Air pressure switch
  • Flue fan assembly
  • Venting tubes
Showing 21–30 of 46
9 E 25

Your boiler is overheating too quickly, so it has automatically shut down for ten minutes to protect itself from heat damage.

High Engineer only £150-300

Parts commonly replaced

  • Circulation pump
  • Primary heat exchanger
  • NTC thermistor sensor
9 E 30

Your boiler has temporarily stopped because it is struggling to circulate water properly through your radiators, causing a large heat difference between the pipes.

Medium DIY-safe £120-250

What to check first

  1. Check that all radiator valves throughout your home are fully open
  2. Bleed your radiators to remove any trapped air that may be blocking water flow
  3. Ensure your system pressure is at the correct level, usually between 1.0 and 1.5 bar

Parts commonly replaced

  • Central heating pump
  • System filter
  • Diverter valve
11.

The internal computer that controls your boiler has experienced a serious processing error and can no longer safely operate the appliance.

High Engineer only £250-450

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Control Module

Related codes

13.

Your boiler's internal computer is experiencing a system error and cannot safely operate the heating or hot water.

High Engineer only £250-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Control Module

Related codes

14.

Your boiler’s internal computer has flagged a critical error that prevents it from starting safely.

High Engineer only £200-350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

15.

Your boiler's main computer brain has detected an internal error and has shut down to prevent further damage.

High Engineer only £250-450

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness
16.

Your boiler's main brain has encountered an internal communication error and cannot safely operate your heating or hot water.

High Engineer only £250-450

Parts commonly replaced

  • Automatic Control Module (PCB)
  • Wiring harness
17.

Your boiler's main computer brain is experiencing an internal error, which has caused it to stop working to ensure your safety.

High Engineer only £250-450

Parts commonly replaced

  • Printed Circuit Board (PCB)
24

Your boiler's temperature sensors have been swapped during installation or maintenance, causing the system to become confused about which way the water is flowing.

High Engineer only £120-200

Parts commonly replaced

  • NTC thermistor wiring harness
  • Flow and return sensors

Related codes

24.

Your boiler's temperature sensors have been swapped over, meaning it cannot correctly measure the heat of the water travelling in and out of the system.

High Engineer only £120-200

Parts commonly replaced

  • NTC Thermistor sensors
  • Wiring harness

Related codes

Showing 31–40 of 46
26.

Your boiler's internal computer has flagged a permanent electronic fault, meaning the system has safely shut down to prevent incorrect operation.

High Engineer only £250-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Wiring harness

Related codes

30

Your boiler has detected that the water leaving the heater is much hotter than the water returning, suggesting a blockage or a failure in the internal pump.

High Engineer only £150-350

Parts commonly replaced

  • Central heating pump
  • Plate heat exchanger
  • System filter

Related codes

30.

Your boiler has detected that the water leaving the unit is significantly hotter than the water returning to it, suggesting a blockage or poor water flow through your heating system.

High Engineer only £120-250

Parts commonly replaced

  • Central heating pump
  • Plate heat exchanger
  • NTC thermistors
31

Your boiler has stopped working because a sensor that measures the temperature of the water currently leaving the unit is providing an invalid reading.

High Engineer only £150-250

Parts commonly replaced

  • NTC Temperature Sensor

Related codes

31.

Your boiler has stopped working because a sensor that measures the water temperature has developed an electrical fault and is giving the system a confusing signal.

High Engineer only £120-200

Parts commonly replaced

  • NTC Temperature Sensor
  • Wiring harness

Related codes

32

Your boiler has identified a faulty sensor that monitors the temperature of the water returning to the system, causing the unit to stop heating as a safety precaution.

High Engineer only £120-220

Parts commonly replaced

  • Return NTC thermistor
  • Wiring harness
32.

Your boiler has detected a faulty electrical signal from a temperature sensor, which is preventing it from heating your home reliably.

High Engineer only £120-220

Parts commonly replaced

  • Return NTC Thermistor
  • Wiring Harness

Related codes

36

Your boiler has stopped working because it is unable to accurately measure the temperature of the water circulating through your radiators.

High Engineer only £120-220

Parts commonly replaced

  • NTC Flow Thermistor
  • Wiring harness
36.

Your boiler has stopped working because a sensor that measures the temperature of the water flowing into your radiators is providing an incorrect reading.

High Engineer only £120-220

Parts commonly replaced

  • NTC flow sensor
  • Wiring harness

Related codes

37

Your boiler is struggling to accurately read the temperature of the water returning to it, so it has shut down to prevent overheating.

High Engineer only £120-200

Parts commonly replaced

  • Return NTC Thermistor
  • Wiring harness

Related codes

Showing 41–46 of 46
37.

Your boiler is struggling to accurately measure the temperature of the water circulating back from your radiators, causing it to stop working as a safety precaution.

High Engineer only £150-250

Parts commonly replaced

  • Heating return NTC thermistor
  • Wiring harness

Related codes

40.

The internal computer that manages your boiler has encountered a serious error and can no longer control the system, meaning your heating and hot water will not work.

High Engineer only £250-450

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Control Module
41.

Your boiler's internal computer is experiencing a critical error and needs to be attended to by a professional to get your heating and hot water back up and running.

High Engineer only £250-450

Parts commonly replaced

  • Printed Circuit Board (PCB)
42.

Your boiler's internal computer has encountered a critical error and can no longer safely manage the heating process, resulting in a system shutdown.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB
  • Control Module
44.

Your boiler's internal computer is experiencing a critical error, which is preventing it from starting up safely.

High Engineer only £250-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Control Module
60.

Your boiler has detected an internal computer error that prevents it from starting safely, meaning you currently have no heating or hot water.

High Engineer only £250-450

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Control Module