Baxi EcoBlue Advance Heat Fault codes & diagnostics

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

Regular Natural Gas 13-30 kW 2014 onwards Discontinued
GC Numbers 41-470-3441-470-3541-470-3641-470-3741-470-3841-470-55
Download the Baxi EcoBlue Advance Heat manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

This boiler uses LED flash patterns

Count the flashes in one repeating group before the pause. That number is your fault code. Do not reset until you have noted it. How to read fault codes →

Severity at a glance

Each cell = one fault code. Hover to identify.
12 High
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
41-470-34 EcoBlue Advance 13 Heat ErP 2014–present
41-470-35 EcoBlue Advance 16 Heat ErP 2014–present
41-470-36 EcoBlue Advance 19 Heat ErP 2014–present
41-470-37 EcoBlue Advance 25 Heat ErP 2014–present
41-470-38 EcoBlue Advance 30 Heat ErP 2014–present
41-470-55 EcoBlue Advance 21 Heat ErP 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.

Just want the most common Baxi EcoBlue Advance Heat faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 12 documented codes

Tap any card for details

1 flash green

Your boiler is overheating because water is not moving through the system quickly enough to be cooled down.

High DIY-safe £100-350

What to check first

  1. Check that your radiator valves are turned on and not closed.
  2. Ensure your external heating pump is running if you have one.
  3. Try resetting the boiler by turning the selector switch to 'R' and then back to 'On'.

Parts commonly replaced

  • Circulation pump
  • Heat exchanger (cleaning/flush)
  • Thermistor (NTC sensor)

Related codes

Full explanation for 1 flash green
1 flash red

Your boiler has detected a problem with how water is moving through the system or a fault with the sensors that monitor temperature.

High DIY-safe £90-220

What to check first

  1. Check that all radiator valves are open
  2. Ensure the external system pump is running (if accessible)
  3. Check that the boiler pressure is between 1 and 1.5 bar
  4. Reset the boiler by turning the selector switch to 'R' for five seconds

Parts commonly replaced

  • Flow temperature sensor (NTC)
  • Return temperature sensor (NTC)
  • External central heating pump

Related codes

Full explanation for 1 flash red
2 flashes green

Your boiler has received an external signal to turn off, usually triggered by an connected thermostat, safety device, or a loose wiring connection.

High DIY-safe £80-180

What to check first

  1. Check if your room thermostat or programmer is turned on and set to a temperature higher than the current room temperature.
  2. Replace the batteries in your room thermostat if it uses them.
  3. Check your fuse box to ensure no heating-related switches have tripped.

Parts commonly replaced

  • External Room Thermostat
  • Wiring Link/Jumper
  • User Interaction Controller

Related codes

Full explanation for 2 flashes green
2 flashes red

Your boiler has sensed it is getting too hot and has shut down as a safety precaution to prevent damage.

High DIY-safe £120-350

What to check first

  1. Check that all radiator valves are fully open to allow water to circulate.
  2. Ensure there is no air trapped in the system by bleeding your radiators.
  3. Press the reset button or turn the selector switch to 'R' for five seconds to see if the fault clears.

Parts commonly replaced

  • Over-heat thermostat
  • Circulation pump
  • Heat exchanger sensor

Related codes

Full explanation for 2 flashes red
3 flashes green

Your boiler was working but the flame has unexpectedly gone out, causing the system to stop as a safety precaution.

High DIY-safe £100-£280

What to check first

  1. Check if other gas appliances (like a hob) are working to ensure your gas supply is active
  2. Check that your gas meter has credit if you use a prepay meter
  3. Press and hold the reset button for five seconds
  4. Check for any frozen external condensate pipes if it is currently freezing weather

Parts commonly replaced

  • Flame sensing electrode
  • Gas valve
  • Ignition lead

Related codes

Full explanation for 3 flashes green
3 flashes red

Your boiler is failing to light the gas or cannot stay lit, meaning you currently have no heating or hot water.

High DIY-safe £100-280

What to check first

  1. Check that your gas pre-payment meter (if you have one) has credit.
  2. Verify that other gas appliances in your home, like a hob, are working correctly.
  3. Reset the boiler by turning the selector switch to the 'R' position for five seconds and then back to its original setting.

Parts commonly replaced

  • Ignition Electrode
  • Gas Valve
  • Flame Sensing Lead
  • PCB

Related codes

Full explanation for 3 flashes red
4 flashes green

Your boiler is having trouble sending messages between its internal electronic parts, meaning it cannot start up to provide heating or hot water.

High Engineer only £100-£350

Parts commonly replaced

  • Main PCB (Control Board)
  • Wiring Harness
  • Display Board

Related codes

Full explanation for 4 flashes green
4 flashes red

Your boiler's fan, which safely pushes exhaust gases out of the flue, is not spinning at the correct speed or has stopped working entirely.

High Engineer only £250-£450

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

Full explanation for 4 flashes red
5 flashes green

Your boiler’s internal computer chip or control board has encountered a software configuration error and cannot start up.

High Engineer only £250-£450

Parts commonly replaced

  • Main PCB
  • Parameter Plug

Related codes

Full explanation for 5 flashes green
5 flashes red

Your boiler's internal computer is having difficulty communicating with its main control unit, meaning it cannot process the settings needed to run safely.

High Engineer only £180-450

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
  • Wiring Harness
  • Parameter Plug

Related codes

Full explanation for 5 flashes red
6 flashes green

Your boiler's internal computer has encountered a processing error and cannot safely manage the burner.

High Engineer only £280-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Control Unit Wiring Loom

Related codes

Full explanation for 6 flashes green
6 flashes red

Your boiler has stopped working because its internal components are struggling to talk to each other or have detected a sequence error.

High Engineer only £100-£350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring Harness
  • External Controls

Related codes

Full explanation for 6 flashes red