Halstead Ace 100 Fault codes & diagnostics

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

Combi Natural Gas 29.3 kW 2006-2011 Discontinued
Download the Halstead Ace 100 manualThe official installation and service manual (PDF), the document these fault codes were read from. 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 →

Fault codes

All 2 documented codes

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Ignition lockout

Your boiler has stopped working because it failed to light the flame, which often happens due to a simple supply issue or a temporary glitch.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Printed Circuit Board (PCB)
Full explanation for Ignition lockout
Safety Lock-out LED

Your boiler has stopped working because it failed to light or has become too hot, causing a safety shutdown to protect your home.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Overheat thermostat
  • Printed Circuit Board (PCB)
Full explanation for Safety Lock-out LED
Status & diagnostic codes

2 operating states & engineer diagnostics

Not faults — these are normal operating states. Tap to expand.

F4 Diagnostic Your boiler has stopped working because an internal electrical safety fuse has blown, preventing the system from powering up safely. Power On LED Status Your boiler is operating normally and is currently set to provide hot water to your taps or shower.