Common problems guide

The most common Biasi Advance 25S problems

The faults most likely to send a Biasi Advance 25S into lockout — with plain-English causes, what to check first, estimated repair costs and whether you need a Gas Safe engineer.

28 documented codes
6 most common
6 DIY-safe checks
0 engineer needed

The 6 most common faults

01
Er 14 High DIY-safe

Your boiler has safely shut itself down due to a safety lock-out, meaning it needs to be manually reset or checked by a professional before it will work again.

What to try first

Locate the reset button or dial on your Biasi boiler control panel.Press and hold the reset button for about 3 to 5 seconds.Wait to see if the boiler fires up normally; if the code returns, do not keep resetting it.

Est. cost
£90-250
Parts
PCB, Ignition Electrode, Gas Valve
Full guide for Er 14
02
Er 06 High DIY-safe

Your boiler has temporarily stopped working for safety reasons and needs to be reset.

What to try first

Locate the reset button on your boiler control panel.Press and hold the reset button for about 5 seconds.Wait to see if the boiler fires up normally; do not repeat this more than twice.

Est. cost
£100-£250
Parts
Ignition Electrode, Gas Valve, Printed Circuit Board (PCB)
Full guide for Er 06
03
Er 04 High DIY-safe

Your boiler has temporarily stopped working as a safety precaution to prevent potential damage.

What to try first

Locate the reset button or turn the mode dial to the reset position on your Biasi boiler.Hold the reset button down for about 2 to 5 seconds and release it.Wait a moment to see if the boiler fires up normally; if the error returns immediately, do not keep resetting it.

Est. cost
£100-250
Parts
Ignition electrode, Gas valve, Printed circuit board (PCB)
Full guide for Er 04
04
Er 03 High DIY-safe

Your boiler has temporarily stopped working as a safety precaution and needs to be reset.

What to try first

Locate the reset button or turn the mode dial to the reset position on your Biasi Advance 25C.Press and hold the reset button for approximately 3 to 5 seconds.Wait to see if the boiler fires up normally; if the code returns, do not keep resetting it.

Est. cost
£90-250
Parts
Ignition electrode, Gas valve, Printed circuit board (PCB)
Full guide for Er 03
05
Er 02 High DIY-safe

Your boiler has temporarily stopped working for safety reasons and needs to be reset.

What to try first

Locate the reset button or turn the mode selector switch to the reset position.Hold the reset button for 2 to 5 seconds and release it.Wait to see if the boiler fires up normally; do not repeat this more than three times.

Est. cost
£90-200
Parts
Ignition electrode, Gas valve, Printed Circuit Board (PCB)
Full guide for Er 02
06
Er 01 High DIY-safe

Your boiler has temporarily stopped working for safety reasons and needs to be manually reset to get it going again.

What to try first

Locate the reset button on your boiler's control panel.Press and hold the reset button for approximately 3 to 5 seconds.Wait to see if the boiler fires up normally; if the error returns, do not keep resetting it.

Est. cost
£100-250
Parts
Ignition electrode, Gas valve, Printed Circuit Board (PCB)
Full guide for Er 01

on the Biasi Advance 25S

PCBIgnition ElectrodeGas ValvePrinted Circuit Board (PCB)Ignition electrodeGas valve

Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.

Call a Gas Safe engineer if…

  • You can smell gas or see signs of a leak
  • The Biasi shows an Emergency or High severity code
  • The boiler keeps locking out after repeated resets
  • You've tried the DIY checks and the fault hasn't cleared
  • There's visible water leaking from the boiler
  • The flame is yellow or orange instead of blue

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See the full 28-code list for the Biasi Advance 25S