Baxi 818 System Fault codes & diagnostics

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

System Natural Gas 18 kW 2019-present
GC Number 41-470-73
Download the Baxi 818 System manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. 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 →

Versions & GC numbers

Which version do you have?

The GC number on your boiler's data badge identifies the exact appliance and production years, as recorded in the UK Product Characteristics Database.

GC number Appliance (register name) Produced
41-470-73 818 SYSTEM 2019–present
Fault codes

All 2 documented codes

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10

Your boiler has detected a critical internal error and has automatically shut down for safety, requiring you to manually restart it.

High Engineer only £120-250

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring Harness
  • Gas Valve

Related codes

Full explanation for 10
110

Your boiler has likely overheated, causing a safety sensor to shut the system down to prevent damage.

High DIY-safe £100-280

What to check first

  1. Check that your radiator valves are open and not blocked by furniture
  2. Ensure your system water pressure is between 1.0 and 1.5 bar
  3. Allow the boiler to cool for 30 minutes and then press the Reset button

Parts commonly replaced

  • Overheat Thermostat (Limit Statutory)
  • Water Pump
  • PCB

Related codes

Full explanation for 110
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