Baxi 630 Combi Fault codes & diagnostics

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

Combi Natural GasLPG 2018-present
GC Numbers 47-077-3247-077-29
Download the Baxi 630 Combi manualThe official installation and service manual (PDF), the document these fault codes were read from. PDF

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Severity at a glance

Each cell = one fault code. Hover to identify.
17 High

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
47-077-32 630 COMBI LPG 30 2018–present
47-077-29 630 Combi 2017–present

Appliance names and production years are taken from the UK Product Characteristics Database (the SAP/SEDBUK register). Where a GC number is also printed in this model's own manufacturer manual, both sources were checked to agree.

All 17 documented codes

Tap any card for details

09

Your boiler has detected an internal electronic or sensor issue and has safely shut down to prevent any potential hazards.

High Engineer only £150-£350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • NTC Thermistor
  • Wiring Harness

Related codes

15

Your boiler has detected an internal communication or general operating fault that prevents it from running safely and efficiently.

High Engineer only £150-350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

20

Your boiler has detected an internal hardware error that prevents it from operating safely.

High Engineer only £150-350

Parts commonly replaced

  • Printed Circuit Board (PCB)

Related codes

28

Your boiler has detected an internal electrical or sensor problem and has safely shut down to prevent any issues.

High Engineer only £150-300

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Temperature Sensor
  • Wiring Harness

Related codes

40

Your boiler has detected an internal hardware error involving one of its main operating components, which will cause it to stop working until it is checked.

High Engineer only £150-350

Parts commonly replaced

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

Related codes

109

Your boiler has detected an internal communication or sensor issue and has safely shut down to prevent any potential risks.

High Engineer only £150-300

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

110

Your boiler has temporarily shut down because the water inside it has become too hot.

High Engineer only £150-300

Parts commonly replaced

  • Heat exchanger
  • NTC thermistor
  • Automatic bypass valve
  • Circulating pump

Related codes

118

Your boiler has temporarily stopped working because the water pressure inside the system has dropped too low.

High DIY-safe

What to check first

  1. Locate the filling loop underneath your boiler or check your user manual for the repressurising procedure.
  2. Open the valves gently to let water in until the pressure gauge reads between 1.0 and 1.5 bar.
  3. Close the valves firmly and press the reset button on your boiler.

Parts commonly replaced

  • Pressure relief valve
  • Pressure sensor
  • Expansion vessel

Related codes

125

Your boiler has detected that the water inside the system is either not heating up properly or is getting far too hot, very quickly.

High Engineer only £150-£350

Parts commonly replaced

  • Pump
  • NTC thermistor
  • Heat exchanger
  • Automatic bypass valve

Related codes

128

Your boiler has temporarily stopped working because the gas flame went out while it was running.

High Engineer only £150-300

Parts commonly replaced

  • Electrodes
  • Gas Valve
  • PCB

Related codes

130

Your boiler has detected an internal electronics or safety fault that requires a trained professional to safely diagnose and resolve.

High Engineer only £150-300

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

133

Your boiler has failed to light because it cannot detect a steady gas flame to keep it running.

High Engineer only £150-300

Parts commonly replaced

  • Ignition lead
  • Electrodes
  • Gas valve
  • PCB

Related codes

134

Your boiler has stopped working because it cannot detect a flame or the gas supply to it has been interrupted.

High Engineer only £100-£250

Parts commonly replaced

  • Ignition lead
  • Electrodes
  • Gas valve
  • Printed Circuit Board (PCB)

Related codes

135

Your boiler has failed to light because it is not detecting a steady gas supply or a flame.

High Engineer only £150-300

Parts commonly replaced

  • Ignition lead
  • Electrodes
  • Gas valve
  • PCB

Related codes

160

Your boiler has detected an internal electrical or component error that requires a professional inspection to resolve safely.

High Engineer only £150-350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Internal wiring harness

Related codes

321

Your boiler has detected an internal electronic or component error that requires a professional inspection to resolve safely.

High Engineer only £150-350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness
  • Internal sensor

Related codes

384

Your boiler has detected an internal electronic or flame stability error and has safely shut down to prevent further issues.

High Engineer only £150-300

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Ignition Electrode
  • Gas Valve

Related codes

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