Common problems guide

The most common Saunier Duval Ecosy 24E problems

The faults most likely to send a Saunier Duval Ecosy 24E into lockout — with plain-English causes, what to check first, estimated repair costs and whether you need a Gas Safe engineer.

This model is discontinued. Parts can be harder to source and expensive. If repair costs are mounting, a new A-rated boiler may be the smarter choice.
46 documented codes
6 most common
4 DIY-safe checks
2 engineer needed

The 6 most common faults

01
1 2 High DIY-safe

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

What to try first

Locate the filling loop (typically a silver braided hose with one or two valves underneath the boiler).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.Close the valve(s) tightly to stop the flow and ensure no water is leaking.

Est. cost
£0-£120
Parts
Filling loop, Pressure relief valve, Pressure sensor
Full guide for 1 2
02
04 High DIY-safe

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

What to try first

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

Est. cost
£80-150
Parts
Main printed circuit board, Power supply cable, Fused spur switch
Full guide for 04
03
1 then 2 High DIY-safe

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

What to try first

Locate the external filling loop, usually a silver braided hose with one or two valves located underneath the boiler.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.Close the valve(s) firmly and ensure there is no water dripping from the connection.

Est. cost
£0-£120
Parts
Filling loop, Pressure relief valve, Expansion vessel
Full guide for 1 then 2
04
04. High DIY-safe

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

What to try first

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

Est. cost
£80-150
Parts
PCB (Printed Circuit Board), Wiring harness, Fused spur
Full guide for 04.
05
1 8 High Engineer

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

Est. cost
£150-250
Parts
NTC Temperature Sensor, Pump, Primary Heat Exchanger
Full guide for 1 8
06
1 9 High Engineer

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.

Est. cost
£120-250
Parts
NTC Return Thermistor, Central Heating Pump, Primary Heat Exchanger
Full guide for 1 9
Parts most often replaced

on the Saunier Duval Ecosy 24E

Filling loopPressure relief valvePressure sensorMain printed circuit boardPower supply cableFused spur switch

Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.

Call a Gas Safe engineer if…

  • You can smell gas or see signs of a leak
  • The Saunier Duval shows an Emergency or High severity code
  • The boiler keeps locking out after repeated resets
  • You've tried the DIY checks and the fault hasn't cleared
  • There's visible water leaking from the boiler
  • The flame is yellow or orange instead of blue
See the full 46-code list for the Saunier Duval Ecosy 24E

Related guides

Boiler losing pressure → No hot water → When to replace → Symptom checker →