Alpha SY Fault codes & diagnostics

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

System Natural Gas 24 kW 2007-2012 Discontinued

Replaced by: InTec 24 S

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Severity at a glance

Each cell = one fault code. Hover to identify.
1 Emergency 6 High 2 Medium

All 9 documented codes

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E01

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

High Engineer only £120-250

Parts commonly replaced

  • Ignition lead
  • Ignition electrode
  • Gas valve

Related codes

E02

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

  • Pump
  • Overheat thermostat
  • Diverter valve
  • Heat exchanger

Related codes

E03

Your boiler has detected an issue with its ventilation or internal air pressure, so it has safely shut down to prevent any unsafe gas build-up.

Emergency Engineer only £120-250

Parts commonly replaced

  • Air pressure switch
  • Flue assembly
  • Venturi
  • Fan unit

Related codes

E04

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

High DIY-safe £80-150

What to check first

  1. Locate the filling loop, which is usually a flexible silver hose connected to two valves beneath the boiler.
  2. Open the valves slowly to allow mains water to enter the system while watching the pressure gauge on the front of the boiler.
  3. Close both valves firmly once the needle reaches the green zone, typically between 1.0 and 1.5 bar.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Pressure sensor

Related codes

E05

Your boiler has lost the ability to accurately measure the temperature of the water circulating through your heating system, so it has shut down as a safety precaution.

High Engineer only £120-220

Parts commonly replaced

  • Flow temperature sensor (NTC)
  • Wiring harness

Related codes

E06

Your boiler is struggling to accurately measure the temperature of your hot water, which means it will stop providing hot taps or showers to prevent overheating.

Medium Engineer only £120-180

Parts commonly replaced

  • DHW NTC sensor
  • Wiring harness

Related codes

E10

Your boiler has detected that the incoming gas pressure is too low to safely ignite or maintain its flame, so it has shut down to prevent issues.

High Engineer only £120-250

Parts commonly replaced

  • Gas pressure switch
  • Gas valve
  • Gas regulator

Related codes

E22

Your boiler's internal computer memory has encountered a data error, meaning it has forgotten how to correctly control your heating and hot water.

High Engineer only £250-450

Parts commonly replaced

  • Printed Circuit Board (PCB)

Related codes

E31

Your boiler is struggling to talk to the wall-mounted thermostat or control unit, meaning it does not know when to turn your heating on or off.

Medium Engineer only £120-250

Parts commonly replaced

  • External controls
  • PCB
  • Wiring loom